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Therefore, velocity of an object measures the rate of change in the position of the object. This implies, if an object travels in a path and reaches the initial point, then the velocity of the object is equal to zero. This is because there is no change in the position of the object.

Displacement is the shortest distance between the initial point and the final point of the object. Displacement is a vector quantity, hence it has both magnitude and direction.

For example in the diagram shown above the person is travelling from point A to point B. Later he travels back from point B to point A. Now the person in back at the initial position. This way the net displacement of the person equals zero. This implies, the velocity of the person equals zero.

In the diagram shown above, a person travels from point A to point B. The curved path shows total distance travelled by the person, whereas the straight line signifies the displacement of the person from point A to point B. This displacement is used to calculate the velocity of the person.

Velocity is calculated as the rate of change of displacement. Displacement is a measure of length and rate is the measure of time. Therefore, in the MKS system the units for displacement is meters and the units for time is seconds, this makes velocity of the object have unit m/s. In CGS system the units for displacement is centimeters and units for time is seconds, this makes velocity of the object have units cm/s

The other commonly used units for velocity are miles/hour (MPH), KMPH, ft. /s.

The velocity of an object can be analyzed using the displacement time graphs. The following are some examples of how the velocity is dependent on the displacement time graph.

In the diagram shown above the displacement of the object is constant with the change in the time. This implies that there is no change in the displacement with respect to time. Hence the velocity of the object is zero.

The displacement time graph shown in the diagram above is a straight line. Here the line has a fixed slope which implies the object is travelling with a constant velocity.

In the diagrams shown above the displacement time graph of an object is a curved line. This implies that the velocity of the object is non-uniform. In the first graph the velocity of the object is increasing. In the second diagram the velocity of the object is decreasing.

The instantaneous velocity is the rate of change in displacement at that point of time. This implies instantaneous velocity is the derivative of displacement with respect to the time. This can be represented as shown below:

b) Here displacement of the car = 20 KM, Time taken for the travel = 2 Hr.

Using the formula for velocity.

Therefore, the velocity of the car = 20 KM/ 2Hr = 10 KMPH.

Therefore the net displacement will be equal to 50 KM.

b) The net displacement of the car = 50 KM.

The time taken by the car = 4 hours.

Using the formula for velocity.

Therefore, the velocity of the car = 50 KM / 4 Hr = 12.5 KMPH

The total time taken for the man to walk = (2 + 1) hour = 3 hour.

Using the formula for velocity.

Therefore, the Average velocity of the man = 9 miles/ 3 hours = 3 miles/hour.

The total time taken for the man to walk = (2 + 1) hour = 3 hour.

Using the formula for velocity.

Therefore, the Average velocity of the man = 3 miles/ 3 hours = 1 miles/hour.