Adam and bobby are twins who have the same weight. adam drops to the ground from a tree at the same time that bobby begins his descent down a frictionless slide. if they both start at the same height of 4 m above the ground, how do their kinetic energies compare when they hit the ground?
a. bobby has greater kinetic energy than adam.
b. adam has greater kinetic energy than bobby.
c. they have the same kinetic energy.
d. bobby has twice the kinetic energy as ad

C. They have the same kinetic energy.

Explanation:

Since Bobby slides down on a frictionless track, his final kinetic energy is equal to his initial potential energy.

Similarly, since Adam is on free-fall, his final kinetic energy will be equal to his initial potential energy.

Considering that they both started at the same height 4m above the ground, their initial potential energies, therefore final kinetic energies will be the same.

we need to know the time interval during which the force acts. impulse of force = momentum change