List two differences in tabular form between speed and velocity. When is a body said to have :
$(a)$ uniform velocity and $(b)$ variable velocity. How is the average velocity of a body is calculated when its velocity changes at a non$-$uniform rate ?

Define 'average speed'. An object moves with a uniform speed of $10\, m s ^{-1}$ for $5 s$ and then with a uniform speed of $5\, m s ^{-1}$ for $10\, s$. Find its average speed.

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

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.

Out of the three speed$-$time graphs shown below

Identify the graph for the following cases.

$(i)$ A ball thrown vertically upwards and returning to the hand of the thrower ?

$(ii)$ A body decelerating to a constant speed and accelerating.