The velocity-time graph for a particle moving in a straight line is shown in the figure. The average velocity between $t=4 \,s$ and $t=6 \,s$ is . . . . . . (in $\,ms^{-1}$)

$A$ body is thrown vertically upwards. Which one of the following graphs correctly represents the velocity vs time?

$A$ train starting from rest travels the first part of its journey with constant acceleration $a$,the second part with constant velocity $v$,and the third part with constant retardation $a$,finally being brought to rest. The average speed for the whole journey is $\frac{7v}{8}$. The train travels with constant velocity for what fraction of the total time?

The instantaneous velocity of a body can be measured by:

The figure shows $(v_x, t)$ and $(v_y, t)$ diagrams for a body of unit mass $(m = 1 \text{ kg})$. Find the force as a function of time.

The position $x$ of a particle with respect to time $t$ along the $x$-axis is given by $x = 9t^2 - t^3$,where $x$ is in metres and $t$ is in seconds. What will be the position of this particle when it achieves maximum speed along the $x$-direction?