$A$ particle is moving in a circular path of radius $r$. The displacement after half a circle would be:

$(a)$ Define uniform circular motion.
$(b)$ Ram goes for a morning walk in a circular park daily. He completes one revolution of the park in $4$ minutes. Find his speed if the diameter of the park is $420\, m$.
$(c)$ Draw velocity$-$time graph for uniform motion along a straight line. How can you find the distance covered by a body from this graph?

What can we conclude about the motion of a body depicted by the following velocity-time graphs?

Two stones are thrown vertically upwards simultaneously with their initial velocities $u_{1}$ and $u_{2}$ respectively. Prove that the heights reached by them would be in the ratio of $u_{1}^{2}: u_{2}^{2}$ (Assume upward acceleration is $-g$ and downward acceleration is $+g$).

Can a body have constant speed and still be accelerating?

The velocity-time graph of cars $A$ and $B$ which start from the same place and move along a straight road in the same direction is shown below.
Calculate:
$(a)$ The acceleration of car $B$ between $2 \, s$ and $4 \, s$.
$(b)$ The time at which both the cars have the same velocity.
$(c)$ The distance travelled by the two cars $A$ and $B$ in $8 \, s$.
$(d)$ Which of the two cars is ahead after $8 \, s$ and by how much?