When sliding a heavy box across the floor, it is often times helpful to lift up on it slightly because
A) You are lessening the friction force by reducing the contact force between the box and the floor
B) You are reducing the weight of the box.
C) You are working against friction by lifting up.
D) You are working against gravity, even if the box does not move upwards.

Question

Quizplus · Accepted Answer

Lifting up on the box slightly reduces the normal force, which is the force perpendicular to the surfaces in contact. Since friction is directly proportional to the normal force, reducing the normal force reduces the friction force, making it easier to slide the box.

When Sliding a Heavy Box Across the Floor, It Is