$A$ body of mass $m$ is moving with velocity $u$ as shown in the figure and it collides with a body of mass $4m$ at rest. If the collision is perfectly inelastic,then the percentage loss in kinetic energy is:

$A$ bullet of mass $m$ moving horizontally with speed $v_0$ hits a wooden block of mass $M$ that is suspended from a massless string. The bullet gets lodged into the block. If the block-bullet system swings to a maximum height $h$,how much of the initial kinetic energy of the bullet is lost in the collision?

$A$ neutron of mass $1.67 \times 10^{-27} \ kg$ moving with a velocity of $10^8 \ m/s$ collides with a deuteron at rest and sticks to it. If the mass of the deuteron is $3.34 \times 10^{-27} \ kg$,what will be the velocity of the combined system?

Two identical blocks of ice move in opposite directions with equal speed and collide with each other. What will be the minimum speed required to make both the blocks melt completely, if the initial temperatures of the blocks were $-8^{\circ} C$ each (in $ms^{-1}$)? (Specific heat of ice is $2100 \ Jkg^{-1} K^{-1}$ and latent heat of fusion of ice is $3.36 \times 10^{5} \ Jkg^{-1}$)

$A$ body of mass $m$ moving with a constant velocity $v$ hits another body of the same mass that is at rest. If the two bodies stick together after the collision,the velocity of the compound body is:

$A$ bullet weighing $10 \,g$ and moving with a velocity $300 \,m/s$ strikes a $5 \,kg$ block of ice and gets embedded in it. The ice block is kept on a smooth surface. The speed of the block after the collision is ........ $cm/s$.