A motor bike running at $90\, km h ^{-1}$ is slowed down to $18 \,km h^{-1}$ in $2.5\, s$. Calculate

$(i)$ acceleration

$(ii)$ distance covered in the time it slows down

What can you say about the motion of an object whose distance time graph is

$(i)$ a straight line, parallel to the time axis ?

$(ii)$ a straight line passing through the origin making an angle with the time axis ?

Draw velocity-time graphs for the following situations

$(i)$ When body is moving with uniform velocity.

$(ii)$ When body is moving with variable velocity, but uniform acceleration.

$(iii)$ When body is moving with variable velocity, but uniform retardation.

$(iv)$ When body is moving with a variable velocity and variable acceleration.

Distinguish between terms speed and velocity.

$(a)$ Differentiate between distance and displacement.

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