How much gravitational potential energy does a 45.2 kg object have when it is 21.9m above the ground?

Anyone who is an expert in for the record, i’m having difficulty understanding the pictures.

Aball is thrown upward in the air, and its height above the ground after t seconds is h ( t ) = 57 t − 16 t 2 feet. find the time t when the ball will be traveling upward at 14.25 feet per second.

The passing of heat through a material while the material itself stays in place. a. radiation b. conduction c. convection