Five objects of different masses are simultaneously released vertically downwards from height $h$ (in air). Which physical quantity associated with the objects will change at the instant they strike the ground? (Neglect the air resistance.)

The figure below shows the position-time graph of a body of mass $0.04 \; kg$. Suggest a suitable physical context for this motion. What is the time between two consecutive impulses received by the body? What is the magnitude of each impulse?

Two billiard balls of equal mass $30 \, g$ strike a rigid wall with the same speed of $108 \, km/h$ (as shown) but at different angles. If the balls get reflected with the same speed, then the ratio of the magnitude of impulses imparted to ball $'a'$ and ball $'b'$ by the wall along the $'X'$ direction is:

The figure shows the position-time graph of a particle of mass $4 \,kg$. What is the
$(a)$ force on the particle for $t < 0$,$t > 4 \,s$,and $0 < t < 4 \,s$?
$(b)$ impulse at $t = 0$ and $t = 4 \,s$? (Consider one-dimensional motion only).

What is impulse of force? Write its unit and dimension.

$A$ $150\, g$ tennis ball coming at a speed of $40\, m/s$ is hit straight back by a bat to a speed of $60\, m/s$. The magnitude of the average force $F$ on the ball,when it is in contact for $5\, ms$,is ........... $N$.