Abdul,while driving to school,computes the average speed for his trip to be $20 \, km \, h^{-1}$. On his return trip along the same route,there is less traffic and the average speed is $40 \, km \, h^{-1}$. What is the average speed (in $km \, h^{-1}$) for Abdul's trip?

Joseph jogs from one end $A$ to the other end $B$ of a straight $300 \, m$ road in $2 \, min$ $30 \, sec$ and then turns around and jogs $100 \, m$ back to point $C$ in another $1 \, min$. What are Joseph's average speeds and velocities in jogging from $A$ to $C$?

$A$ driver of a car travelling at $52\, km\, h^{-1}$ applies the brakes and accelerates uniformly in the opposite direction. The car stops in $5\, s$. Another driver going at $3\, km\, h^{-1}$ in another car applies his brakes slowly and stops in $10\, s$. On the same graph paper,plot the speed versus time graphs for the two cars. Which of the two cars travelled farther after the brakes were applied?

$A$ train is travelling at a speed of $90\, km \,h^{-1}$. Brakes are applied so as to produce a uniform acceleration of $-0.5\, m s^{-2}$. Find how far (in $m$) the train will go before it is brought to rest.

$A$ motorboat starting from rest on a lake accelerates in a straight line at a constant rate of $3.0 \, m s^{-2}$ for $8.0 \, s$. How far does the boat travel (in $m$) during this time?

Distinguish between speed and velocity.