3 problems and solutions about the Speed equation
1. A car travels to the south for 100 m in 1 minute then turns to the east 120 m in 0.5 minutes. Determine the average speed of the car.
Known:
Total distance = 100 meters + 120 meters = 220 meters
Total time = 1 minute + 0.5 minutes = 1.5 minutes = 90 seconds
Wanted: Average speed
Solution:
Speed formula
Average speed = total distance : total time = 220 meters : 90 seconds = 2.4 meters/second
2. A boat traveling in a straight line for a distance of 100 meters after 10 seconds. What is the average speed of the boat?
Known:
Distance = 100 meters
Time = 10 seconds
Wanted: Average speed
Solution:
Speed formula
Average speed = 100 meters : 10 seconds = 10 meters/second
3. A particle moves from point O to point B in 4 s and from B to A in 20 s. Determine the average speed of the particles.
Known:
Distance of OB = 5 meters
Distance of BA = 8 meters
Time of OB = 4 seconds
Time of BA = 20 seconds
Wanted: The average speed of the particles
Solution:
Speed formula
The average speed of the particles = total distance : total time = (5 + 8) : (4 + 20) = 13 : 24 = 0.54 meter/second
Conceptual questions and answer about speed
What is speed? Speed is a scalar quantity that refers to “how fast an object is moving.” It is the rate at which an object covers distance.
What is the difference between speed and velocity? While speed is a scalar quantity indicating “how fast an object moves,” velocity is a vector quantity that refers to “the speed of an object in a particular direction.”
What is the formula for speed? Speed (v) is calculated by dividing the total distance travelled (d) by the total time taken (t). So, v = d/t.
What are the units of speed in the SI system? The SI unit for speed is meters per second (m/s).
How is the speed of a moving body measured? The speed of a moving body can be measured using a variety of instruments, such as a speedometer in a vehicle or a radar gun for moving balls in sports.
What is average speed? Average speed is the total distance travelled by an object divided by the total time taken to travel that distance. It is a measure of distance covered per unit time.
What is instantaneous speed? Instantaneous speed is the speed of an object at a specific instant in time. It can be found by taking the derivative of the distance with respect to time.
What does a speed-time graph represent? A speed-time graph represents how an object’s speed changes over time. The gradient of the graph gives the acceleration, and the area under the graph gives the distance travelled.
What is the difference between uniform and variable speed? Uniform speed means that an object covers equal distances in equal intervals of time. Variable speed means that an object covers different distances in equal intervals of time.
How does acceleration relate to speed? Acceleration is the rate of change of velocity (and thus speed, in the case of straight-line motion) with respect to time. If an object is speeding up, it has positive acceleration; if it’s slowing down, it has negative acceleration.
What is the speed of light? The speed of light in a vacuum, denoted by ‘c’, is a fundamental physical constant, approximately equal to 3.00×10⁸ m/s.
Can anything move faster than the speed of light? According to our current understanding of physics, as laid out in Einstein’s theory of relativity, no information or matter can travel faster than the speed of light in a vacuum.
What is Mach speed? Mach number is a dimensionless quantity representing the speed of an object moving through a fluid medium or the speed of a fluid relative to an object, divided by the speed of sound in that medium.
How does increasing the mass of an object affect its speed? In the absence of net external forces, increasing the mass of an object does not affect its speed. However, if a force is applied, a more massive object will accelerate less and thus its speed will increase slower than for a less massive object.
What is terminal speed? Terminal speed (or terminal velocity) is the constant maximum speed reached by an object falling through a fluid (like air) under the forces of gravity and drag.
What is escape speed? Escape speed (or escape velocity) is the minimum speed an object needs to escape the gravitational pull of a planet or other body, without propulsion
