The masses of blocks $A$ and $B$ are $100 \, kg$ and $200 \, kg$ respectively. The coefficient of friction between $A$ and $B$ is $0.2$,and the coefficient of friction between $B$ and the ground is $0.3$. What force $F$ (in $N$) must be applied to block $B$ to make it move?

$A$ man balances himself in a horizontal position by pushing his hands and feet against two parallel walls. His centre of mass lies midway between the walls. The coefficients of friction at the walls are equal. Which of the following is not correct?

In the given system,if $M_2 = 2M_1$,the tension in the string is $T$. If the positions of the blocks are interchanged,what will be the new tension in the string?

$A$ hosepipe directs a horizontal jet of water moving with a velocity of $20\, m/s$ onto a vertical wall. The cross-sectional area of the jet is $10^{-3}\, m^2$. If the density of water is $1000\, kg/m^3$,then the force acting on the wall is ........... $N$ [Assuming water comes to rest after striking the wall].

$A$ block of mass $m$ is placed on a smooth horizontal surface. $A$ force making an angle $\theta$ with the horizontal starts acting on the block. The magnitude of the force is constant but its direction with the horizontal changes as $\theta = a + bs$,where $a$ and $b$ are constants and $s$ is the distance covered by the block. If $|F| = 2mb$,find the velocity of the block as a function of the angle $\theta$.

$A$ bullet of mass $0.1\,kg$ moving horizontally with speed $400\,m/s$ hits a wooden block of mass $3.9\,kg$ kept on a horizontal rough surface. The bullet gets embedded into the block and moves $20\,m$ before coming to rest. The coefficient of friction between the block and the surface is $........$ (Given $g=10\,m/s^2$)