From the given displacement-time graph, answer the following questions:

(i) The kind of motion depicted in this graph is :

1. uniform
2. non-uniform
3. retardation
4. all of the above

(ii) The velocity between point A and C is:

1. 20 ms^-1
2. 5 ms^-1
3. 10 ms^-1
4. 15 ms^-1

(iii) The displacement at t = 3s is:

1. 15 m/s²
2. 12.5 m/s²
3. 40 m
4. 30 m

(i) uniform
Reason — As the graph shows the linear relationship between displacement and time i.e., the car travels equal distance in equal intervals of time in a certain direction. Thus, it is moving with uniform motion.

(ii) 10 ms^-1
Reason — As, velocity is the ratio of displacement and time, therefore,

$\text{Velocity} = \text{Slope of straight line AC} \\[0.5em] = \dfrac{(60 - 30) \text{ m}}{(5 - 2) \text{ s}} \\[0.5em] = \dfrac{30 \text{ m}}{3 \text{ s}} \\[0.5em] = 10 \text{ m s}^{-1}$

(iii) 40 m
Reason — When we observe the graph, we notice that at t = 3 s, the displacement axis shows 40 m, hence, displacement at t = 3 s is 40 m