$A$ ball of mass $0.1 \, kg$ coming with a speed of $30 \, m/s$ strikes a bat and returns in the opposite direction with a speed of $40 \, m/s$. Calculate the impulse. (Take the final velocity as positive.)

$A$ book is lying on the table. What is the angle between the action of the book on the table and the reaction of the table on the book?

$A$ ball of mass $m$ moves with speed $v$ and strikes a wall normally and is reflected back normally. If its time of contact with the wall is $t$,find the force exerted by the ball on the wall.

$A$ soccer ball of mass $250 \text{ g}$ is moving horizontally to the left with a speed $22 \text{ ms}^{-1}$. This ball is kicked towards the right with a velocity $30 \text{ ms}^{-1}$ at an angle $53^{\circ}$ with the horizontal in the upward direction. Assuming that it took $0.01 \text{ s}$ for the collision to take place, the average force acting is $(\cos 53^{\circ} = \frac{3}{5}; \sin 53^{\circ} = \frac{4}{5})$. (in $\text{ N}$)

$A$ block of mass $2 \ kg$ moves freely along the $x$-axis. It is at rest at $t = 0$. The force $F(t)$ acting on the block varies with time $t$ as shown in the figure. What is the kinetic energy of the block after $4.5 \ s$ (in $J$)?

$A$ wall is hit elastically and normally by $n$ balls per second. All the balls have the same mass $m$ and are moving with the same velocity $u$. The force exerted by the balls on the wall is