4) Two objects, A with mass of 3.0 kg and object B with mass of 1.0 kg, move on a frictionless horizontal surface. Object A moves to the right at a constant velocity of 5.0 m/s, while object B moves to the left at a constant velocity of -2.0 m/s. They collide and bounce off one another (a perfectly elastic collision). Object A is now moving to the left at -2.0 m/s, A. Determine the total momentum of the system (both objects) before the collision B. What is the velocity of object B after the collision?

Aballoon is rising vertically upwards at a velocity of 10m/s. when it is at a height of 45m from the ground, a parachute bails out from it. after 3s he opens his parachute and decelerates ata a constant rate 5m/s.when. (a) what was the height of the parachutist above the ground when he opened his parachute? (b)how far is the parachutist from the balloon at t=3s? (c)with what velocity does the parachutist hit the ground? (d)after how long does the parachutist hit the ground after his exist from the balloon?