{"id":4621,"date":"2021-06-27T16:51:40","date_gmt":"2021-06-27T23:51:40","guid":{"rendered":"https:\/\/gurumuda.net\/physics\/?p=4621"},"modified":"2023-08-01T12:04:17","modified_gmt":"2023-08-01T12:04:17","slug":"free-fall-motion","status":"publish","type":"post","link":"https:\/\/gurumuda.net\/physics\/free-fall-motion.htm","title":{"rendered":"Free fall motion","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"<h3 style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">Article about the Free fall motion<\/span><\/h3>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">In everyday life, we often see objects that experience free-fall motion, for example, the motion of fruit falling from a tree, the motion of objects that fall or are dropped from a certain height. Why do objects experience free-fall motion? If observed at a glance, the object experiencing free fall as if it has a fixed speed, or in other words the object does not accelerate. The fact that happens, every object that falls freely experiences a constant acceleration. This reason causes free-fall motion, including the example of nonuniform linear motion. How to prove that objects experiencing free-fall experience <a href=\"https:\/\/gurumuda.net\/physics\/constant-acceleration-problems-and-solutions.htm\">constant acceleration<\/a> or its speed increase?<!--more--><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">Plug two nails in the ground and drop a stone from a different height on each nail. You will see that the nails that are subjected to stones at a higher level are stuck deeper than the other nails. The higher the stone position from the ground surface, the greater the speed of the stone when it strikes the ground so that it presses the nail deeper.<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">In the past, the motion of objects falling to the ground was a very intriguing subject in natural philosophy. Aristotle, a philosopher, once said that an object that has a bigger mass falls faster than lighter objects. Aristotle&#8217;s opinion influenced the views of people who lived before Galileo&#8217;s time, who considered that objects with a larger mass fall faster than lighter objects and that the speed of falling objects was proportional to the mass of the object. Maybe before learning this subject, you also think so. For example, we drop a piece of paper and a rock from the same height. The results we observed indicate that the stone first touched the ground or floor surface than paper. Now, let&#8217;s drop two stones from the same height, where one stone is bigger than the other. The two stones touched the surface of the ground at the same time, compared to the stone and paper we dropped earlier. We can also experiment with dropping stones and paper in the form of lumps.<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">What influences the movement of falling rocks or paper? Air friction force! Air resistance or friction greatly affects free-fall motion. Galileo postulates that all objects will fall with the same acceleration if there is no air or other obstacles. Galileo asserted that all objects, heavy or light, fall with the same acceleration, at least if there is no air. Galileo believes that air acts as an obstacle to extremely light objects that have a large surface. But in many situations, this air resistance can be ignored. In a room where the air has been sucked (vacuum), light objects such as a piece of paper held horizontally will fall with the same acceleration as other objects. Galileo&#8217;s contribution to our understanding of the motion of falling objects can be summarized as follows: <\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">At a particular location on earth and lacking air resistance, all objects fall with the same constant acceleration. We call this acceleration caused by gravity and give it a symbol g. The magnitude of g is approximately 9.8 m\/s<sup>2<\/sup>. In English System units, the magnitude of g is approximately 32 ft\/s<sup>2<\/sup>. The direction of the acceleration of gravity toward the center of the earth.<\/span><\/p>\n<h3 class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\"><b>Definition of the free fall motion<\/b><\/span><\/h3>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">An object is said to experience free fall if the object moves perpendicular to the center of the earth and during its motion, the object experiences the constant acceleration of gravity. If the free-fall near the surface of the earth, then the object experiences a constant acceleration of gravity of 9.8 m\/s<sup>2<\/sup><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">and the direction of acceleration of gravity towards the center of the earth (perpendicular to the surface of the earth). To simplify the calculations, g is 10 m\/s<sup>2<\/sup>. <\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">There are three different situations:<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">1. Objects move vertically down without initial speed (no v<sub>o<\/sub>). For example, the fruit falls from the tree after being released from the stem. The direction of movement is always downward and the object experiences acceleration so that g is always positive. In certain physics books called free-fall motion.<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">2. The object moves vertically down with the initial speed (there is v<sub>o<\/sub>). For example, a stone thrown vertically downward. The direction of movement is always downward and the object experiences acceleration so that g is always positive. In certain physics books, it is called vertical downward motion.<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">3. The object move vertically upward at an initial speed, after reaching maximum height, the object moves back downward. Suppose you throw vertical marbles up and catch them again when the marbles move down. When moving upward, objects experience a deceleration (negative g), when moving vertically down, the object accelerates (g positive). In certain physics books, it is called vertical upward motion. It should be noted that if an object experiences one of the three conditions above, the object is said to do the free-fall motion.<\/span><\/p>\n<h3 class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\"><b>The equation of the free fall motion<\/b><\/span><\/h3>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">Free-fall motion is an example of nonuniform linear motion, therefore the equation of the free-fall motion is basically the same as the equation of the nonuniform linear motion and adjusted to the conditions in the free-fall motion.<\/span><\/p>\n<p style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-medium wp-image-4622\" src=\"https:\/\/gurumuda.net\/physics\/wp-content\/uploads\/2018\/10\/Free-fall-motion-1-300x129.png\" alt=\"Free fall motion 1\" width=\"300\" height=\"129\" srcset=\"https:\/\/gurumuda.net\/physics\/wp-content\/uploads\/sites\/28\/2018\/10\/Free-fall-motion-1-300x129.png 300w, https:\/\/gurumuda.net\/physics\/wp-content\/uploads\/sites\/28\/2018\/10\/Free-fall-motion-1.png 430w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/span><\/p>\n<p style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-medium wp-image-4623\" src=\"https:\/\/gurumuda.net\/physics\/wp-content\/uploads\/2018\/10\/Free-fall-motion-2-300x128.png\" alt=\"Free fall motion 2\" width=\"300\" height=\"128\" srcset=\"https:\/\/gurumuda.net\/physics\/wp-content\/uploads\/sites\/28\/2018\/10\/Free-fall-motion-2-300x128.png 300w, https:\/\/gurumuda.net\/physics\/wp-content\/uploads\/sites\/28\/2018\/10\/Free-fall-motion-2.png 432w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">h = height (meter), v<sub>o <\/sub>= initial speed (meter\/second), v<sub>t<\/sub> = final speed (meter\/second), t = time (second), g = acceleration of gravity (meter\/second) = 9.8 m\/s<sup>2<\/sup> or 10 m\/s<sup>2<\/sup>.<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">The acceleration of gravity is constant at 10 m\/s<sup>2<\/sup> (g positive, the object moves downward) means that the speed of the object increases by 10 m\/s every 1 second. 2 seconds later, the object speed increases by 20 m\/s. 3 seconds later, the object speed increases by 30 m\/s. Constant deceleration of gravity is 10 m\/s<sup>2<\/sup> (g negative, the object moves upward) means that the speed of the object decreases by 10 m\/s every 1 second. 2 seconds later, the speed of the object decreases by 20 m\/s. 3 seconds later, the speed of the object decreases by 30 m\/s. Constant acceleration or constant deceleration only occurs near the surface of the earth.<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">Sample problem 1:<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">Mango is released and falls to the ground. If the initial position is 10 meters from the ground surface and the mass of mango is 5 grams, determine:<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">(a) the speed of the mango when it arrives at the ground<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">(b) the time interval for the mango to reach the ground.<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">g = 9.8 m\/s<sup>2<\/sup><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">Solution:<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><u>Known:<\/u> h = 10 m, g = 9.8 m\/s<sup>2<\/sup><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">a) The speed of manga when it arrives at the ground<\/span><\/p>\n<p style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-4624\" src=\"https:\/\/gurumuda.net\/physics\/wp-content\/uploads\/2018\/10\/Free-fall-motion-3.png\" alt=\"Free fall motion 3\" width=\"265\" height=\"50\" \/><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">Mass is calculated in the equation of the free-fall motion<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">b) Time interval in air<\/span><\/p>\n<p style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-4625\" src=\"https:\/\/gurumuda.net\/physics\/wp-content\/uploads\/2018\/10\/Free-fall-motion-4.png\" alt=\"Free fall motion 4\" width=\"132\" height=\"69\" \/><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">Sample problem 2:<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">An object is dropped from a certain height. Determine:<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">(a) the magnitude of the object acceleration<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">(b) the distance traveled by the object for the first 2 seconds<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">(c) the speed of the object after falling 50 meters<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">(d) how much time is needed for the object to reach a speed of 20 m\/s,<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">(e) how much time is needed for the object to fall as far as 100 meters<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\"><u>Solution:<\/u><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><u>Known:<\/u> g = 9.8 m\/s<sup>2<\/sup><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">a) The magnitude of the acceleration of the object<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">Acceleration of the object = acceleration of gravity = g = 9.8 m\/s<sup>2<\/sup><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">b) The distance traveled by the object for the first 2 seconds<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><u>Known:<\/u> g = 9.8 m\/s<sup>2 <\/sup>, t = 2 s<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><u>Wanted:<\/u> h<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">h = 1\u20442 g t<sup>2 <\/sup>= 1\u20442 (9.8)(2)<sup>2<\/sup> = (4.9)(4) = 19.6 meters<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">c) The speed of the object after falling as far as 50 meters<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><u>Known:<\/u> h = 50 m, g = 9,8 m\/s<sup>2<\/sup><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><u>Wanted:<\/u> v<sub>t<\/sub><\/span><\/p>\n<p style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-4626\" src=\"https:\/\/gurumuda.net\/physics\/wp-content\/uploads\/2018\/10\/Free-fall-motion-5.png\" alt=\"Free fall motion 5\" width=\"292\" height=\"27\" \/><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">d) How much time is needed for objects to reach a speed of 20 m\/s<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><u>Known:<\/u> v<sub>t <\/sub>= 20 m\/s, g = 9,8 m\/s<sup>2<\/sup><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><u>Wanted:<\/u> t<\/span><\/p>\n<p style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-4627\" src=\"https:\/\/gurumuda.net\/physics\/wp-content\/uploads\/2018\/10\/Free-fall-motion-6.png\" alt=\"Free fall motion 6\" width=\"144\" height=\"45\" \/><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">e) The time interval needed for objects to fall as far as 100 meters<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><u>Wanted: <\/u>h = 100 m, g = 9,8 m\/s<sup>2<\/sup><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><u>Solution:<\/u> t<\/span><\/p>\n<p style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-4628\" src=\"https:\/\/gurumuda.net\/physics\/wp-content\/uploads\/2018\/10\/Free-fall-motion-7.png\" alt=\"Free fall motion 7\" width=\"281\" height=\"74\" \/><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">Sample problem 3 :<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">A stone is thrown into a well with an initial speed of 5 m\/s. If the stone falls in water after 4 seconds, determine:<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">(a) the speed of the stone when it comes into water<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">(b) the depth of the well<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">Solution:<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">a) Speed of stone when it comes into water<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\"><u>Known:<\/u><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">v<sub>o<\/sub> = 5 m\/s, t = 4 s, g = 9.8 m\/s<sup>2<\/sup><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><u>Wanted:<\/u> v<sub>t<\/sub><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">v<sub>t <\/sub>= v<sub>o<\/sub> + g t<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">v<sub>t<\/sub> = 5 m\/s + (9.8 m\/s<sup>2<\/sup>)(4 s) = 5 m\/s + 39.2 m\/s<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">v<sub>t <\/sub>= 44.2 m\/s<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">b) Well depth<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\"><u>Known:<\/u><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">v<sub>o<\/sub> = 5 m\/s, t = 4 s, g = 9.8 m\/s<sup>2<\/sup><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><u>Wanted:<\/u> h<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">h = v<sub>o<\/sub> t + \u00bd g t<sup>2<\/sup><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">h = (5)(4) + \u00bd (9.8)(4)<sup>2<\/sup><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">h = 20 + (4.9)(16)<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">h = 20 + 78.4<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">h = 98.4 meters<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">Sample problem 4:<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">From the top of the building as high as 50 meters, a package is thrown vertically downward at a speed of 10 m\/s. Determine:<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">(a) The time in the air<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">(b) The speed of the package when strikes the ground<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">Solution:<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">a) The time in air<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\"><u>Known:<\/u><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">h = 50 m, g = 9.8 m\/s<sup>2<\/sup>, v<sub>o <\/sub>= 10 m\/s<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><u>Wanted:<\/u> t<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">h = v<sub>o<\/sub> t + \u00bd g t<sup>2<\/sup><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">50 = 10 t + \u00bd (9.8) t<sup>2<\/sup><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">50 = 10 t + 4.9 t<sup>2<\/sup><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">4.9 t<sup>2 <\/sup>+ 10 t \u2013 50 = 0<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">Use quadratic formula:<\/span><\/p>\n<p style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-medium wp-image-4629\" src=\"https:\/\/gurumuda.net\/physics\/wp-content\/uploads\/2018\/10\/Free-fall-motion-8-292x300.png\" alt=\"Free fall motion 8\" width=\"292\" height=\"300\" srcset=\"https:\/\/gurumuda.net\/physics\/wp-content\/uploads\/sites\/28\/2018\/10\/Free-fall-motion-8-292x300.png 292w, https:\/\/gurumuda.net\/physics\/wp-content\/uploads\/sites\/28\/2018\/10\/Free-fall-motion-8.png 310w\" sizes=\"auto, (max-width: 292px) 100vw, 292px\" \/><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">Time in air = 2.3 seconds<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">b) The speed of the package when strikes the ground<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\"><u>Known:<\/u><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">h = 50 m, g = 9.8 m\/s<sup>2<\/sup>, v<sub>o <\/sub>= 10 m\/s<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><u>Wanted: <\/u>v<sub>t<\/sub><\/span><\/p>\n<p style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-4630\" src=\"https:\/\/gurumuda.net\/physics\/wp-content\/uploads\/2018\/10\/Free-fall-motion-9.png\" alt=\"Free fall motion 9\" width=\"215\" height=\"75\" \/><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">Sample problem 5:<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">A ball is thrown vertically upward at an initial speed of 20 m\/s. Determine the maximum height reached by the ball.<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">Solution:<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">The quantities of the vector whose direction is upward are positive, the quantities of the vector whose direction is downward are negative. The initial position of the ball is chosen as the reference point.<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\"><u>Known:<\/u><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">v<sub>o <\/sub>= 20 m\/s (direction of initial speed is upward, the ball is thrown upward, so v<sub>o<\/sub> is positive)<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">v<sub>t <\/sub>= 0 m\/s (speed of ball at the maximum height is 0 m\/s)<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">g = &#8211; 9.8 m\/s<sup>2<\/sup> (direction of the acceleration of gravity is downward, so g is negative)<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><u>Wanted:<\/u> h<\/span><\/p>\n<p style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-4634\" src=\"https:\/\/gurumuda.net\/physics\/wp-content\/uploads\/2018\/10\/Free-fall-motion-10.png\" alt=\"Free fall motion &#096;10\" width=\"107\" height=\"203\" \/><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">Sample problem 6:<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">A marble is thrown vertically upward from a top of a building 100 meters above the ground at an initial speed of 20 m\/s. Determine:<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">(a) Time in air<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">(b) the speed of marble when strikes the ground<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">Solution:<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">Position where the marble is thrown as the reference point; the top of the building is a reference point. The magnitude of the vector whose direction is upward is positive, the magnitude of the vector whose direction is downward is negative.<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">a) Time in air<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\"><u>Known:<\/u><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">h = &#8211; 100 m (h is negative because the ground surface is below the initial position or reference point)<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">v<sub>o<\/sub> = 20 m\/s (direction of the initial speed is upward, so v<sub>o<\/sub> is positive)<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">g = &#8211; 9.8 m\/s<sup>2 <\/sup>(direction of the acceleration of gravity is downward, so g is negative)<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><u>Wanted:<\/u> t<\/span><\/p>\n<p style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-4631\" src=\"https:\/\/gurumuda.net\/physics\/wp-content\/uploads\/2018\/10\/Free-fall-motion-11.png\" alt=\"Free fall motion 11\" width=\"160\" height=\"124\" \/><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">Use the quadratic formula:<\/span><\/p>\n<p style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-medium wp-image-4632\" src=\"https:\/\/gurumuda.net\/physics\/wp-content\/uploads\/2018\/10\/Free-fall-motion-12-243x300.png\" alt=\"Free fall motion 12\" width=\"243\" height=\"300\" srcset=\"https:\/\/gurumuda.net\/physics\/wp-content\/uploads\/sites\/28\/2018\/10\/Free-fall-motion-12-243x300.png 243w, https:\/\/gurumuda.net\/physics\/wp-content\/uploads\/sites\/28\/2018\/10\/Free-fall-motion-12.png 292w\" sizes=\"auto, (max-width: 243px) 100vw, 243px\" \/><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">The time needed to reach the ground since<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">the ball is thrown = 7 seconds.<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">b) The speed of marble when strikes the surface of the ground<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\"><u>Known:<\/u><\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">h = -100 m (negative because the ground surface is below the reference point or initial position)<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-family: 'times new roman', times, serif;font-size: 12pt\">v<sub>o<\/sub> = 20 m\/s (the direction of the initial speed is upward, so v<sub>o<\/sub> is positive)<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">g = -9.8 m\/s<sup>2 <\/sup>(direction of the acceleration of gravity is downward, so g is negative).<\/span><\/p>\n<p class=\"western\" style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><u>Wanted:<\/u> v<sub>t<\/sub><\/span><\/p>\n<p style=\"text-align: justify\" align=\"justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-4633\" src=\"https:\/\/gurumuda.net\/physics\/wp-content\/uploads\/2018\/10\/Free-fall-motion-13.png\" alt=\"Free fall motion 13\" width=\"257\" height=\"100\" \/><\/span><\/p>\n<p style=\"text-align: justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>Conceptual questions and answer about Free fall motion<\/strong><\/span><\/p>\n<ol style=\"text-align: justify\">\n<li><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>What is free fall motion?<\/strong><\/span>\n<p><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">Free fall motion is the motion of an object under the influence of gravity alone, with no other forces acting on it, such as air resistance.<\/span><\/li>\n<li><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>What is the acceleration due to gravity?<\/strong><\/span>\n<p><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">Acceleration due to gravity is the acceleration that an object experiences when falling freely near the surface of the Earth. It is typically denoted as &#8216;g&#8217; and has an approximate value of 9.8 m\/s\u00b2.<\/span><\/li>\n<li><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>What is the formula for displacement in free fall motion, given initial velocity and time?<\/strong><\/span>\n<p><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">The formula is h = ut + \u00bdgt\u00b2, where h is displacement (height), u is initial velocity, g is acceleration due to gravity, and t is time.<\/span><\/li>\n<li><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>How does the velocity of an object change during free fall motion?<\/strong><\/span>\n<p><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">During free fall, an object&#8217;s velocity increases linearly over time due to the constant acceleration of gravity.<\/span><\/li>\n<li><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>What is the formula for final velocity in free fall motion, given initial velocity and time?<\/strong><\/span>\n<p><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">The formula is v = u + gt, where v is final velocity, u is initial velocity, and g is acceleration due to gravity.<\/span><\/li>\n<li><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>What happens to the velocity of an object at the peak of its trajectory in free fall motion?<\/strong><\/span>\n<p><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">At the peak of its trajectory, the velocity of the object becomes zero momentarily.<\/span><\/li>\n<li><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>What does a negative sign represent in the context of free fall motion?<\/strong><\/span>\n<p><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">The negative sign usually denotes a direction opposite to the chosen positive direction. Depending on the context, it can indicate falling down (if up is positive) or thrown down (if up is negative).<\/span><\/li>\n<li><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>What happens to the acceleration of an object in free fall when it reaches its maximum height?<\/strong><\/span>\n<p><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">The acceleration of an object at its maximum height in free fall remains equal to g (approximately -9.8 m\/s\u00b2 near the Earth&#8217;s surface), pointing downward.<\/span><\/li>\n<li><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>How does air resistance affect free fall motion?<\/strong><\/span>\n<p><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">In reality, air resistance can significantly slow an object&#8217;s descent, making the motion no longer a free fall. However, in many physics problems, air resistance is ignored for simplicity.<\/span><\/li>\n<li><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>What is the time of flight in free fall motion?<\/strong><\/span><\/li>\n<\/ol>\n<p style=\"text-align: justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\">The time of flight is the total time that the object spends in the air. For an object launched and landing at the same height, the time of flight can be found by the formula t = 2u\/g.<\/span><\/p>\n<p style=\"text-align: justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>Problems and solutions about Free fall motion<\/strong><\/span><\/p>\n<ol>\n<li style=\"text-align: justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>Problem:<\/strong> A rock is dropped from a cliff of height 78.4 meters. How long does it take for the rock to reach the ground? <strong>Solution:<\/strong> We use the equation h = \u00bdgt\u00b2. Solving for time, t = \u221a(2h\/g) = \u221a(2&#215;78.4\/9.8) = 4 s.<\/span><\/li>\n<li style=\"text-align: justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>Problem:<\/strong> A ball is thrown upwards with an initial velocity of 19.6 m\/s. How high does the ball go? <strong>Solution:<\/strong> Using the equation h = v\u2080t &#8211; \u00bdgt\u00b2 at maximum height (where final velocity is 0), the height h = v\u2080\u00b2 \/ (2g) = (19.6)\u00b2 \/ (2&#215;9.8) = 20 m.<\/span><\/li>\n<li style=\"text-align: justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>Problem:<\/strong> A stone is thrown upwards with an initial velocity of 10 m\/s. What will be its velocity after 2 seconds? <strong>Solution:<\/strong> The equation v = v\u2080 &#8211; gt gives velocity v = 10 &#8211; 9.8&#215;2 = -9.6 m\/s.<\/span><\/li>\n<li style=\"text-align: justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>Problem:<\/strong> A coin is dropped down a well and hits the water after 3 seconds. How deep is the well? <strong>Solution:<\/strong> Using h = \u00bdgt\u00b2, the depth h = \u00bdx9.8&#215;3\u00b2 = 44.1 m.<\/span><\/li>\n<li style=\"text-align: justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>Problem:<\/strong> A book falls off a table and hits the ground after 0.5 seconds. How high was the table? <strong>Solution:<\/strong> Using h = \u00bdgt\u00b2, the height h = \u00bdx9.8x(0.5)\u00b2 = 1.225 m.<\/span><\/li>\n<li style=\"text-align: justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>Problem:<\/strong> A ball is thrown upwards with an initial velocity of 20 m\/s. When will it reach its maximum height? <strong>Solution:<\/strong> At maximum height, v = 0. Solving t = (v &#8211; v\u2080) \/ -g, the time t = (0 &#8211; 20) \/ -9.8 = 2.04 s.<\/span><\/li>\n<li style=\"text-align: justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>Problem:<\/strong> An object falls for 6 seconds. What is its final velocity? <strong>Solution:<\/strong> Using v = v\u2080 + gt with initial velocity v\u2080 = 0, the final velocity v = 0 + 9.8&#215;6 = 58.8 m\/s.<\/span><\/li>\n<li style=\"text-align: justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>Problem:<\/strong> An apple falls from a tree and takes 1.5 seconds to hit the ground. What was the height of the tree? <strong>Solution:<\/strong> Using h = \u00bdgt\u00b2, the height h = \u00bdx9.8x(1.5)\u00b2 = 11 m.<\/span><\/li>\n<li style=\"text-align: justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>Problem:<\/strong> A soccer ball is kicked vertically upwards with an initial velocity of 25 m\/s. How long until it hits the ground? <strong>Solution:<\/strong> Time to maximum height t = v\u2080 \/ g = 25 \/ 9.8 = 2.55 s. The total time to hit the ground is twice this, so t = 2&#215;2.55 = 5.1 s.<\/span><\/li>\n<li style=\"text-align: justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>Problem:<\/strong> A stone is dropped off a bridge and hits the water after 4 seconds. How high is the bridge? <strong>Solution:<\/strong> Using h = \u00bdgt\u00b2, the height h = \u00bdx9.8&#215;4\u00b2 = 78.4 m.<\/span><\/li>\n<li style=\"text-align: justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>Problem:<\/strong> A rocket is launched straight up at 50 m\/s. How high does it go? <strong>Solution:<\/strong> Using h = v\u2080\u00b2 \/ (2g), the height h = (50)\u00b2 \/ (2&#215;9.8) = 127.55 m.<\/span><\/li>\n<li style=\"text-align: justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>Problem:<\/strong> A ball is thrown downwards with an initial speed of 10 m\/s. What is its velocity after 2 seconds? <strong>Solution:<\/strong> Using v = v\u2080 + gt, the velocity v = 10 + 9.8&#215;2 = 29.6 m\/s.<\/span><\/li>\n<li style=\"text-align: justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>Problem:<\/strong> A ball is thrown vertically upwards and returns to the ground in 6 seconds. What was its initial velocity? <strong>Solution:<\/strong> Using v\u2080 = gt \/ 2 (since total time is twice the time to reach maximum height), the initial velocity v\u2080 = 9.8&#215;6 \/ 2 = 29.4 m\/s.<\/span><\/li>\n<li style=\"text-align: justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>Problem:<\/strong> An object falls for 10 seconds. How far does it fall? <strong>Solution:<\/strong> Using h = \u00bdgt\u00b2, the distance h = \u00bdx9.8&#215;10\u00b2 = 490 m.<\/span><\/li>\n<li style=\"text-align: justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>Problem:<\/strong> A marble is dropped from a tower and takes 5 seconds to hit the ground. How high is the tower? <strong>Solution:<\/strong> Using h = \u00bdgt\u00b2, the height h = \u00bdx9.8&#215;5\u00b2 = 122.5 m.<\/span><\/li>\n<li style=\"text-align: justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>Problem:<\/strong> A baseball is thrown vertically upwards with an initial velocity of 15 m\/s. When will it reach its maximum height? <strong>Solution:<\/strong> At maximum height, v = 0. Solving t = (v &#8211; v\u2080) \/ -g, the time t = (0 &#8211; 15) \/ -9.8 = 1.53 s.<\/span><\/li>\n<li style=\"text-align: justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>Problem:<\/strong> An object is dropped and falls for 7 seconds. What is its final velocity? <strong>Solution:<\/strong> Using v = v\u2080 + gt with initial velocity v\u2080 = 0, the final velocity v = 0 + 9.8&#215;7 = 68.6 m\/s.<\/span><\/li>\n<li style=\"text-align: justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>Problem:<\/strong> A rock is thrown upwards with an initial velocity of 30 m\/s. What will be its velocity after 3 seconds? <strong>Solution:<\/strong> Using v = v\u2080 &#8211; gt, the velocity v = 30 &#8211; 9.8&#215;3 = 0.6 m\/s.<\/span><\/li>\n<li style=\"text-align: justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>Problem:<\/strong> A stone is dropped from a cliff and hits the ground after 8 seconds. How high is the cliff? <strong>Solution:<\/strong> Using h = \u00bdgt\u00b2, the height h = \u00bdx9.8&#215;8\u00b2 = 313.6 m.<\/span><\/li>\n<li>\n<p style=\"text-align: justify\"><span style=\"font-size: 12pt;font-family: 'times new roman', times, serif\"><strong>Problem:<\/strong> An arrow is shot straight up at 60 m\/s. How long until it hits the ground? <strong>Solution:<\/strong> Time to maximum height t = v\u2080 \/ g = 60 \/ 9.8 = 6.12 s. The total time to hit the ground is twice this, so t = 2&#215;6.12 = 12.24 s.<\/span><\/p>\n<\/li>\n<\/ol>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"<p>Article about the Free fall motion In everyday life, we often see objects that experience free-fall motion, for example, the motion of fruit falling from a tree, the motion of objects that fall or are dropped from a certain height. Why do objects experience free-fall motion? If observed at a glance, the object experiencing free &#8230; <a title=\"Free fall motion\" class=\"read-more\" href=\"https:\/\/gurumuda.net\/physics\/free-fall-motion.htm\" aria-label=\"Read more about Free fall motion\">Read more<\/a><\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_seopress_titles_title":"","_seopress_titles_desc":"Definition of the free fall motion An object free fall if moves perpendicular to the center of the earth caused by the acceleration of gravity.","_seopress_robots_index":"","_seopress_robots_follow":"","_seopress_robots_imageindex":"","_seopress_robots_snippet":"","_seopress_robots_primary_cat":"","_seopress_robots_breadcrumbs":"","_seopress_robots_freeze_modified_date":"","_seopress_robots_custom_modified_date":"","_seopress_robots_canonical":"","_seopress_social_fb_title":"","_seopress_social_fb_desc":"","_seopress_social_fb_img":"","_seopress_social_fb_img_attachment_id":0,"_seopress_social_fb_img_width":0,"_seopress_social_fb_img_height":0,"_seopress_social_twitter_title":"","_seopress_social_twitter_desc":"","_seopress_social_twitter_img":"","_seopress_social_twitter_img_attachment_id":0,"_seopress_social_twitter_img_width":0,"_seopress_social_twitter_img_height":0,"_seopress_redirections_value":"","_seopress_redirections_enabled":"","_seopress_redirections_enabled_regex":"","_seopress_redirections_logged_status":"","_seopress_redirections_param":"","_seopress_redirections_type":0,"_seopress_analysis_target_kw":"Free fall motion","_seopress_news_disabled":"","_seopress_video_disabled":"","_seopress_video":[],"_seopress_pro_schemas_manual":[],"_seopress_pro_rich_snippets_disable_all":"","_seopress_pro_rich_snippets_disable":[],"_seopress_pro_schemas":[],"footnotes":""},"categories":[2],"tags":[],"class_list":["post-4621","post","type-post","status-publish","format-standard","hentry","category-basic-physics-tutorials"],"gt_translate_keys":[{"key":"link","format":"url"}],"_links":{"self":[{"href":"https:\/\/gurumuda.net\/physics\/wp-json\/wp\/v2\/posts\/4621","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/gurumuda.net\/physics\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/gurumuda.net\/physics\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/gurumuda.net\/physics\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/gurumuda.net\/physics\/wp-json\/wp\/v2\/comments?post=4621"}],"version-history":[{"count":2,"href":"https:\/\/gurumuda.net\/physics\/wp-json\/wp\/v2\/posts\/4621\/revisions"}],"predecessor-version":[{"id":8425,"href":"https:\/\/gurumuda.net\/physics\/wp-json\/wp\/v2\/posts\/4621\/revisions\/8425"}],"wp:attachment":[{"href":"https:\/\/gurumuda.net\/physics\/wp-json\/wp\/v2\/media?parent=4621"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/gurumuda.net\/physics\/wp-json\/wp\/v2\/categories?post=4621"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/gurumuda.net\/physics\/wp-json\/wp\/v2\/tags?post=4621"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}