Question

A brick is dropped from rest from the top of a building through air (air resistance is present) to the ground below. how does the brick's kinetic energy just before reaching the ground compare with the gravitational potential energy at the top of the building? set zero height at the ground level. the comparison cannot be made since the information of air resistance is not given. kinetic energy just before reaching the ground < gravitational potential energy at the top of the building kinetic energy just before reaching the ground = gravitational potential energy at the top of the building kinetic energy just before reaching the ground > gravitational potential energy at the top of the building

Answer 1

The correct option is this: KINETIC ENERGY JUST BEFORE REACHING THE GROUND IS LESS THAN THE GRAVITATIONAL POTENTIAL ENERGY AT THE TOP OF THE BUILDING.
When the object was on the top of the building, it has potential energy. This potential energy was converted to kinetic energy when the object started falling. In the process of falling, friction was present, which means that some of the energy will be converted to heat as a result of the friction. Therefore the kinetic energy of the falling object will be less than its potential energy, because some of the energy has been spent on friction.<span />