91Ó°ÊÓ

From the above graph and the data given, it is clear that the velocity increases from time t = 0 s to t = 3 s.

Figure: 2.58

From time t = 3 s to time t = 18 s, the velocity of the body is not at all changing.

Hence the velocity is constant, so the body is undergoing uniform motion.

From t = 18 s to t = 23 s, the velocity of the body decreases.

Hence, in the initial case, the velocity increases rapidly up to $\mathbf{3}\mathbf{seconds}$, then the velocity is constant.

So the position versus time graph will be as below:

Figure: Position versus time

Hence the graph of position versus time will be similar to this.

Here the person is traveling with constant velocity from 3 to 18 s. hence there will not be a change in the velocity.

If there is no change in velocity, then acceleration will be zero.

The person's velocity is increasing from 0 to $\mathbf{3}\mathbf{}\mathbf{seconds}$. Hence there will be a constant acceleration.

In the other case, 18 to 23 s the person speed is decreasing hence there will be retardation.

Acceleration is obtained by the slope of the velocity vs. time graph.