A horse pulls a 80 kg cart while moving at a rate of 3 m/s. The horse and driver hear a wolf howl in the distance and increases its speed to 7 m/s out of fear. What amount of work did the horse have to do in order to increase the kinetic energy of the cart?

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?