The displacement of a body is proportional to the cube of the time lapsed. The magnitude of the acceleration is

$(a)$ What is acceleration ? Write its $SI$ unit.

$(b)$ Draw velocity-time graph, when an object has

$(i)$ uniformly accelerated velocity

$(ii)$ uniformly retarded velocity.

The nelocitu$-$time graph of a body is as shown. What tupe of motion does the body posses ?

If the displacement$-$time graph for a particle is parallel to time axis, what is the velocity of the particle ?

Distance$-$time graph below represents the motion of two buses $A$ and $B$

$(i)$ What is the distance by which bus $B$ was ahead of bus $A$ initially ?

$(ii)$ Do they ever meet each other ? If so, when ?

$(iii)$ What is the distance travelled by bus $A$ when it overtakes bus $B$ ?

$(iv)$ Find out the distance by which bus $A$ was ahead of bus $B$ at $y=12 h$

$(v)$ Which one of them is moving faster ? Give reason.

An athlete completes one round of a circular track of diameter $49 \,m$ in $20 \,s$. Calculate the distance covered and displacement at the end of $30 \,s$.