Consider an elastic collision of a particle of mass $m$ moving with velocity $u$ with another particle of the same mass $m$ at rest. After the collision, the particles move at angles $\theta_1$ and $\theta_2$ with respect to the initial direction of motion. What is the sum of the angles $\theta_1 + \theta_2$ in degrees?

$A$ ball of mass $m$ moving with velocity $v$ undergoes an elastic collision with another ball of the same mass $m$ moving in the opposite direction with velocity $2v$. What will be their velocities after the collision?

$A$ smooth sphere $A$ moves on a frictionless horizontal surface with an angular velocity $\omega$ and a linear velocity $v$ of its center of mass. It undergoes an elastic collision with another identical sphere $B$ at rest. Neglecting friction everywhere,if the angular speeds after the collision are $\omega_A$ and $\omega_B$ respectively,then:

$A$ ball $A$ of mass $m$ moving along the positive $x$-direction with kinetic energy $K$ and momentum $p$ undergoes an elastic head-on collision with a stationary ball $B$ of mass $M$. After the collision,the ball $A$ moves along the negative $x$-direction with kinetic energy $K/9$. The final momentum of $B$ is:

$A$ body of mass $5\, kg$ moving with a velocity $10\, m/s$ collides with another body of mass $20\, kg$ at rest and comes to rest. The velocity of the second body due to the collision is ............ $m/s$.

As per the given figure,a small ball $P$ slides down the quadrant of a circle and hits another ball $Q$ of equal mass which is initially at rest. Neglecting the effect of friction and assuming the collision to be elastic,the velocity of ball $Q$ after the collision will be $............\,m/s$ $(g = 10\,m/s^2)$.