$A$ tennis ball is dropped onto the floor from a height of $9.8\,m$. It rebounds to a height of $5.0\,m$. The ball comes in contact with the floor for $0.2\,s$. The average acceleration during contact is $..........\,m/s^2$. [Given $g = 10\,m/s^2$]

The average force necessary to stop a hammer having momentum $50 \ N-s$ in $0.25 \ s$ is ...... $N$.

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

$A$ $140\, g$ ball,in horizontal flight with a speed $v_1$ of $39.0\, m/s$,is struck by a bat. After leaving the bat,the ball travels in the opposite direction with speed $v_2 = 39.0\, m/s$. If the impact time $\Delta t$ for the ball-bat collision is $1.20\, ms$,what average net force acts on the ball? (in $N$)

When a bullet is fired from a rifle, its momentum becomes $20 \,kg \cdot m/s$. If the velocity of the bullet is $1000 \,m/s$, then what is its mass?

$A$ $100 \, g$ iron ball having a velocity of $10 \, m/s$ collides with a wall at an angle of $30^\circ$ with the wall surface and rebounds with the same angle. If the period of contact between the ball and the wall is $0.1 \, s$,then the force experienced by the ball is ............. $N$.