$A$ body of mass $m$ moves with velocity $v$ in the East direction,and another body of the same mass moves with velocity $v$ in the North direction. After they collide and stick together,what is the combined velocity of the resulting body of mass $2m$?

$A$ bullet of mass $m$ travelling with a speed $v$ hits a block of mass $M$ initially at rest and gets embedded in it. The combined system is free to move and there is no other force acting on the system. The heat generated in the process will be

$A$ moving body of mass $m$ and velocity $3 \, km/h$ collides with a body of mass $2m$ at rest and sticks to it. Now the combined mass starts to move. What will be the combined velocity in $km/h$?

$A$ block of mass $4 m$ travelling at a velocity $v_1$ in the $x$-direction on a frictionless horizontal plane makes a head-on collision with another block of mass $2 m$ travelling in the opposite direction with a velocity $v_2$. After the collision,both blocks travel as a single block along the $x$-direction with a final velocity $5 v_2$. The ratio of velocities $\frac{v_1}{v_2}$ is

$A$ ball moving horizontally with a velocity $2 \,ms^{-1}$ strikes the bob of a seconds pendulum at rest. If the mass of the bob is equal to the mass of the ball and the collision is perfectly elastic, after collision the bob of the pendulum will raise to a height of $(g=10 \,ms^{-2})$ (in $\,cm$)

$A$ bullet of mass $m$ and velocity $v$ when fired at a sand bag of mass $M$,suspended by a string,gets embedded into the bag. The loss of kinetic energy in this process is