Define velocity.

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 $30 \,s$.

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 $+g$).

The speed-time graphs of two cars are represented by $P$ and $Q$ as shown below.
$(a)$ Find the difference in the distance travelled by the two cars (in $m$) after $4\, s$.
$(b)$ Do they ever move with the same speed? If so,when?
$(c)$ What type of motion are car $P$ and car $Q$ undergoing?

What is the relation between distance and time:
$(i)$ when a body is moving with uniform velocity?
$(ii)$ when a body is moving with variable velocity?

Account for the following:
$(a)$ What is the shape of the path of a body when it is in uniform motion?
$(b)$ Give one example of non-uniform motion.
$(c)$ Two cars $A$ and $B$ have their $x-t$ graph as shown in the figure. Which has greater velocity?
$(d)$ What is the quantity which is measured by the area occupied below the velocity-time graph?
$(e)$ $A$ body is moving with a velocity of $10 \, m/s$. If the motion is uniform,what will be the velocity after $10 \, s$?