Find the accelerations $a_1, a_2$ and $a_3$ of the blocks if a $10\,N$ force $F$ is applied on the $3\,kg$ block as shown in the figure.

$A$ $10 \, kg$ ball attached to the end of a rigid massless rod of length $L = 1 \, m$ rotates at a constant speed in a horizontal circle of radius $r = 0.5 \, m$ and period $T = 1.57 \, s$ as shown in the figure. The force exerted by the rod on the ball is ........ $N$.

$A$ metal block is resting on a rough wooden surface. $A$ horizontal force applied to the block is increased uniformly with time,i.e.,$F = kt$. Which of the following curves correctly represents the velocity $v$ of the block as a function of time $t$?

$A$ particle of mass $m$ falls from rest through a resistive medium having a resistive force,$F = -kv$,where $v$ is the velocity of the particle and $k$ is a constant. Which of the following graphs represents velocity $(v)$ versus time $(t)$?

$A$ person is managing to be at rest between two vertical walls by pressing one wall with his hands and feet and the second wall with his back. The coefficient of friction is $0.5$ between his body and the walls. If the force with which the person pushes the walls is $500 \ N$,then the mass of the person is (Take $g = 10 \ m \ s^{-2}$) (in $kg$)

On a stationary sail-boat,air is blown at the sails from a fan attached to the boat. The boat will