Question

efficiency of machines quick check
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
friction between the truck and the inclined plane.
friction between lenore and the ground.
friction between the box and the inclined plane.
friction between lenore’s hands and the box.

Explanation:

To determine where energy is lost as heat due to friction when pushing a box up an inclined plane, we analyze each option:

• Friction between the truck and the inclined plane: The truck and inclined plane are stationary relative to each other during the box - pushing, so no relative motion means no friction - induced energy loss here.
• Friction between Lenore and the ground: Lenore's movement relative to the ground (if any) isn't directly related to the box's motion up the plane. The main energy loss for the box's motion is due to its interaction with the plane.
• Friction between the box and the inclined plane: As the box slides (or is pushed) up the inclined plane, there is relative motion between the box and the plane. Friction opposes this motion, and work done against friction is converted to heat, resulting in energy loss.
• Friction between Lenore’s hands and the box: The friction here helps Lenore push the box (it's a necessary force for her to apply the push), and it's not a source of energy loss for the box's motion up the plane (instead, it's a force that enables the transfer of her applied force to the box).

Answer:

C. Friction between the box and the inclined plane