Question

Lenore is on an inclined plane next to her truck. Holding her hands steady, she pushes a box
up the plane and into her truck. Where can energy be lost?
Friction between Lenore and the ground.
Friction between the truck and the inclined plane.
Friction between the box and the inclined plane.
Friction between Lenore’s hands and the box.

Answer 1

Friction is the main source of energy loss in this scenario. Energy can be lost through friction between Lenore and the ground, between the truck and the inclined plane, between the box and the inclined plane, and between Lenore's hands and the box. Each of these sources of friction causes some of the energy that Lenore is expending to be converted into heat and sound instead of being used to move the box into the truck.