$A$ bullet of mass $40 \,g$ is fired from a gun of mass $10 \,kg$. If the velocity of the bullet is $400 \,m/s$,then the recoil velocity of the gun will be ..........

$A$ stationary particle explodes into two particles of masses $m_1$ and $m_2$ which move in opposite directions with velocities $v_1$ and $v_2$. The ratio of their kinetic energies $E_1/E_2$ is:

$A$ shell of mass $200\, g$ is ejected from a gun of mass $4\, kg$ by an explosion that generates $1.05\, kJ$ of energy. The initial velocity of the shell is .............. $m/s$.

$A$ cat with mass $m_c$ is sitting at rest on the left plank of a pair of identical planks. Each plank has mass $m_s$ and they rest on frictionless ice. Suddenly,the cat leaps to the right plank,traveling with a horizontal speed $v_{cg}$ measured with respect to the ground. The instant the cat reaches the right plank,it turns around and leaps back to the left plank. The horizontal component of the cat's speed is again $v_{cg}$ measured with respect to the ground. The final speed of the right plank in terms of the masses of the cat and planks and the cat's leaping speed is (The cat remains on the left plank after its return).

$A$ stationary particle explodes into two particles of masses $x$ and $y$,which move in opposite directions with velocities $v_1$ and $v_2$. The ratio of their kinetic energies $(E_1: E_2)$ is

$A$ body is moving with a velocity $v$ and breaks up into two equal parts. One of the parts retraces its path with velocity $v$. Then the velocity of the other part is: