The frictional force of the floor on a large suitcase is least when the suitcase is
A) pushed by a force parallel to the floor.
B) dragged by a force parallel to the floor.
C) pulled by a force directed at an angle θ above the floor.
D) pushed by a force directed at an angle θ into the floor.
E) turned on its side and pushed by a force parallel to the floor.

Question

Quizplus · Accepted Answer

When a force is applied at an angle above the floor, it partially lifts the suitcase, reducing the normal force and, consequently, the frictional force, as friction depends on the normal force between the surfaces.

The Frictional Force of the Floor on a Large Suitcase