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