Four balls are thrown off the top of a building 27 m high.All balls are thrown with identical speeds,but at different angles.Ball 1 is thrown straight upward.Ball 2 is thrown straight downward.Ball 3 is thrown at an angle of +45 $\circ$ relative to the horizontal.And Ball 4 is thrown at an angle of -45 $\circ$ relative to the horizontal.Which ball has the greatest kinetic energy when it hits the ground?

Question

Quizplus · Accepted Answer

All four balls are thrown with identical speeds, therefore they have the same initial potential energy. The difference in their final kinetic energies is due to the different paths they take and the work done by gravity. However, since they all end up at the same height and with the same speed, they have the same kinetic energy when they hit the ground. Therefore, the answer is E, all have the same kinetic energy.

Four Balls Are Thrown Off the Top of a Building ∘\circ∘

Four Balls Are Thrown Off the Top of a Building $\circ$