Before learning about average speed and average velocity, we must know the difference between distance and displacement.
Distance is a scalar quantity which generally implies how much ground has been covered by the object. On the other hand, displacement is a vector quantity, and it is the shortest possible distance between the start and end point.
Speed vs. Velocity
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Speed: Speed is defined as the distance traveled by an object per unit time. It is a scalar quantity, which means that it only takes into account the magnitude of the motion of the object, not the direction.
Velocity: Velocity is defined as the displacement of an object per unit time. It is a vector quantity, which means that it takes both the magnitude and direction of the motion of the object into account.
Average speed
Average speed is the total distance traveled by an object divided by the time taken to cover that distance. It is a scalar quantity that tells us the average rate at which an object covers the distance.
The formula for calculating average speed is:
Average speed = Total distance traveled / Total time taken
For example, if a person walks 2 kilometers in 30 minutes, then the average speed of that person can be calculated as:
Average speed = Total distance traveled / Total time taken
= 2 km / 0.5 hours
= 4 km/hour
Therefore, the average speed of the person is 4 kilometers per hour.
Another example, if a car travels 200 kilometers in 4 hours, then the average speed of the car can be calculated as:
Average speed = Total distance traveled / Total time taken
= 200 km / 4 hours
=50 km/hour
Therefore, the average speed of the car is 50 kilometers per hour.
It is important to note that average speed does not tell us anything about the direction of the motion of an object. It only gives us information about the rate at which the distance is being covered.
Average velocity
Average velocity is the displacement of an object divided by the time taken to cover that displacement. It is a vector quantity that tells us the average rate and direction of motion of an object over a given time interval.
The formula for calculating average velocity is:
Average velocity = Displacement / Time taken
For example, if a person walks 2 kilometers north in 30 minutes and then walks back 2 kilometers south in another 30 minutes, then the displacement of that person can be calculated as:
Displacement = Final position – Initial position
= (0 km north – 2 km south)
= -2 km
Therefore, the average velocity of the person can be calculated as:
Average velocity = Displacement / Time taken
= -2 km / 1 hour
= -2 km/hour south
Therefore, the average velocity of the person is 2 kilometers per hour south.
Another example, if a car travels 200 kilometers north in 4 hours and then travels 100 kilometers south in the next 2 hours, then the displacement of the car can be calculated as:
Displacement = Final position – Initial position
= (100 km south – 200 km north)
= -100 km
Therefore, the average velocity of the car can be calculated as:
Average velocity = Displacement / Time taken
= -100 km / 6 hours
= -16.67 km/hour north
Therefore, the average velocity of the car is 16.67 kilometers per hour south.
It is important to note that average velocity takes into account both the magnitude and direction of the motion of an object. It gives us information about the average rate and direction of motion of an object over a given time interval.
