A hemisphere of radius $R$ and of mass $4m$ is free to slide with its base on a smooth horizontal table. A particle of mass $m$ is placed on the top of the hemisphere. The angular velocity of the particle relative to hemisphere at an angular displacement $\theta $ when velocity of hemisphere $v$ is

Two spheres $A$ and $B$ of masses $m_1$ and $m_2$ respectively collide. $A$ is at rest initially and $B$ is moving with velocity $v$ along $x-$ axis. After collision $B$  has a $\frac {v}{2}$ velocity in a direction perpendicular to the original direction. The mass $A$ moves after collision in the direction

Two identical billiard balls strike a rigid wall with the same speed but at different angles, and get reflected without any change in speed, as shown in Figure. What is

$(i)$ the direction of the force on the wall due to each ball?

$(ii)$ the ratio of the magnitudes of impulses imparted to the balls by the wall ?

A stationary body of mass $m$ gets exploded in $3$ parts having mass in the ratio of $1 : 3 : 3$. Its two fractions having equal mass moving at right angle to each other with velocity of $15\,m/sec$. Then the velocity of the third body is

$A$ system of $N$ particles is free from any external forces. Which of the following is true for the magnitude of the total momentum of the system?

An object of mass $2 \,kg$ at rest at origin starts moving under the action of a force $\vec{F}=\left(3 t^2 \hat{i}+4 \hat{j}\right) N$ The velocity of the object at $t=2 \,s$ will be ............. $m / s$