$A$ ball connected with a string is released at an angle of $45^{\circ}$ with the vertical,as shown in the figure. If the mass of the box is equal to the mass of the ball,the acceleration of the box at this instant will be:

Three blocks with masses $m$,$2m$,and $3m$ are connected by strings,as shown in the figure. After an upward force $F$ is applied on block $m$,the masses move upward at a constant speed $v$. What is the net force on the block of mass $2m$? ($g$ is the acceleration due to gravity)

$A$ balloon with mass $m$ is descending down with an acceleration $a$ (where $a < g$). How much mass should be removed from it so that it starts moving up with an acceleration $a$?

$A$ body of mass $2 \ kg$ is acted upon by two forces each of magnitude $1 \ N$ and inclined at $60^{\circ}$ with each other. The acceleration of the body in $m/s^2$ is $[\cos 60^{\circ}=0.5]$

$A$ bullet of mass $0.1\, kg$ is fired into a wooden block to pierce through it,but it stops after moving a distance of $50\, cm$ into it. If the velocity of the bullet before hitting the wood is $10\, m/s$ and it slows down with uniform deceleration,then the magnitude of the effective retarding force on the bullet is $'x'\, N$. The value of $'x'$ to the nearest integer is:

$A$ body of mass $3 \, kg$ hits a wall at an angle of $60^\circ$ with the wall and returns at the same angle. The speed of the body is $10 \, m/s$ and the impact time is $0.2 \, s$. Calculate the force exerted on the wall.