$A$ 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.

Why are porcelain objects wrapped in paper or straw before packing for transportation?

In the figure shown,a balloon is pressed against a wall. It is in equilibrium and maximum compressed state. $\vec F_1 =$ force of balloon on hand of man; $\vec F_2 =$ force of balloon on wall; $\vec F_3 =$ friction; $\vec F_4 =$ weight of balloon. Choose the correct statement.

$A$ particle moves in the $x-y$ plane under the influence of a force $\vec{F}$ such that its linear momentum is $\vec{P}(t) = \hat{i} \cos(kt) - \hat{j} \sin(kt)$. If $k$ is a constant,the angle between $\vec{F}$ and $\vec{P}$ will be:

$A$ ball of mass $150\,g$ starts moving with an acceleration of $20\,m/s^2$. When hit by a force,which acts on it for $0.1\,s$. The impulsive force is ........ $N-s$.

$A$ 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 $g = 10\,m/s^2$]