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?

Which of the following is true for displacement ?

$(a)$ It cannot be zero.

$(b)$ Its magnitude is greater than the distance travelled by the object.

Distinguish between speed and velocity.

What does the odometer of an automobile measure ?

A bus starting from rest moves with a uniform acceleration of $0.1\, m s^{-2}$ for $2\,min$. Find $(a)$ the speed acquired, $(b)$ the distance travelled.