Give an expression for the speed of an athlete if he takes time $'t^{\prime}$ to go around a circular track, of radius ${ }^{\prime} r^{\prime}$

Account for the following

$(a)$ Name the quantity which is measured by the area occupied below the velocity$-$time graph.

$(b)$ An object is moving in a certain direction with acceleration in the perpendicular directions.

$(c)$ Under what condition is the magnitude of average velocity of an object equal to its average speed ?

$(d)$ An example of uniformly accelerated motion.

$(e)$ A body is moving along a circular path of radius

$(r)$. What will be the distance and displacement of the body when it completes half revolution ?

Write true or false for the following statements

A body is said to be at rest, if it does not change its position with respect to the reference point.

What do uou understand by the term acceleration ? When is it positive and when is it negative ?

A scooter starts from rest moves in a straight line with a constant acceleration and covers a distance of $64 \,m$ in $4 \,s$

$(i)$ Calculate its acceleration and its final velocity.

$(ii)$ At what time the scooter had covered half the total distance ?