$A$ car travels from point $A$ to point $B$ with a speed of $40 \ km/h$ and returns from $B$ to $A$ with a speed of $60 \ km/h$. What is the average speed of the car for the entire journey (in $km/h$)?

$A$ vehicle runs on a straight road of length $L$. It travels half the distance with speed $V$ and the remaining distance with speed $\frac{V}{3}$. Its average speed is

Write the relation between speed and the magnitude of velocity.

$A$ car covers a distance at a speed of $60 \ km \ h^{-1}$. It returns and comes back to the original point moving at a speed of $V$. If the average speed for the round trip is $48 \ km \ h^{-1}$,then the magnitude of $V$ is (in $km \ h^{-1}$)

If the average velocity of a particle moving on a straight line is zero in a time interval,then:

The position of an object moving along the $x$-axis is given by $x = a + b t^2$,where $a = 8.5 \; m$,$b = 2.5 \; m s^{-2}$,and $t$ is measured in seconds. What is the average velocity between $t = 2.0 \; s$ and $t = 4.0 \; s$ (in $; m s^{-1}$)?