Question

The velocity-time graph of a body is as shown in the graph:

1. State the kind of motion represented by OA and AB.

2. What is the velocity of the body after 10 s and after 30 s?

3. Calculate retardation of the body.

4. Calculate the distance covered by the body between 10th and 30th second.

Answer 1

(1) OA represents uniform acceleration since the slope of OA in the velocity-time graph is having a uniform positive slope. AB represents the uniform velocity of 20 ms^-1. Since the slope of AB is zero hence, acceleration is zero.

(2) After 10s, the velocity is 20 ms^-1 up to 30s and after 30 s, the velocity is uniformly restarted to zero after 40 s.

(3) Retardation is uniform and it is equal to the slope of BC, i.e.

slope of BC = \(\frac{BD}{DC}=\frac{20}{40-30}\) = 2ms^-2

And acceleration = -2 ms^-2

(4) Distance covered by the body between the 10th and 30th second

= 20 x 20 = 400 metres