Two bodies $$A$$ and $$B$$ of same mass undergo completely inelastic one dimensional collision. The body $$A$$ moves with velocity $$v_1$$ while body $$B$$ is at rest before collision. The velocity of the system after collision is $$v_2$$. The ratio $$v_1: v_2$$ is

A bullet of mass $$m$$ hits a block of mass $$M$$ elastically. The transfer of energy is the maximum, when :

Two particles A and B initially at rest, move towards each other under mutual force of attraction. At an instance when the speed of A is v and speed of B is 3v, the speed of centre of mass is :

A $$1 \mathrm{~kg}$$ object strikes a wall with velocity $$1 \mathrm{~m} \mathrm{~s}^{-1}$$ at an angle of $$60^{\circ}$$ with the wall and reflects at the same angle. If it remains in contact with wall for $$0.1 \mathrm{~s}$$, then the force exerted on the wall is :