Forces and Laws...

Student A and student B sit in identical office chairs facing each other, as shown in figure. Student A is heavier than student B. Student A suddenly pushes student B with his feet. Suppose $$v_A$$ and $$v_B$$ are the velocities of student A and student B respectively, then

Two solid rubber balls, $$A$$ and $$B$$ having masses $$200 \ g$$ and $$400 \ g$$ respectively are moving in opposite directions with velocity of $$A$$ equal to $$0.3\:m/s$$. After collision the two balls come to rest, then the velocity of $$B$$ is-

The 35 kilogram girl is standing on a 20 kilogram wagon and jumps off, giving the wagon a kick that sends it off at 3.8 meters per second. How fast is the girl moving?

A space-craft of mass $$M$$ moves with a velocity $$V$$ and suddenly explodes into two pieces. If a part of mass $$m$$ becomes stationary, then the velocity of another part will be :

If a constant external force starts acting on a moving particle, then:

A bullet of mass m = 50 gm strikes a bag of mass M = 5 kg hanging from a fixed point, with a horizontal velocity $$\bar{V}_p$$. If bullet sticks to the sand bag then just after collision the ratio of final & initial kinetic energy of the bullet is approximately :

Four forces are acting on a body. If the body doesn't change its position or shape, the forces :

A soldier with a machine gun, falling from an airplane gets detached from his parachute. He is able to resist the downward acceleration if the shoots 40 bullets a second at the speed of 500 m/s. If the mass of a bullet is 49 gm, what is the mass of the man with the gun ? Ignore resistance due to air and assume the acceleration due to gravity g = 9.8 $$m/s^2$$.

A massive ball moving with speed v collides head-on with a tiny ball at rest having a very small mass as compared to the first ball. If the collision is elastic, then immediately after the impact, the second ball will move with a speed approximately equal to 

A body $$A$$ of mass $$150 \ kg$$, travelling at $$20 \ m/s$$ collides with a body $$B$$ of mass $$100 \ kg$$ travelling at $$10 \ m/s$$ in the same direction. After collision the velocity of $$A$$ becomes $$15 \ m/s$$. What is the magnitude of velocity of $$B$$ after the collision?