A small mass and a large mass are in contact with each other while resting on a smooth table. An external force is applied to one of the masses (in a direction toward the other mass). The contact force between the masses is
A) largest when the external force is applied to the smaller mass.
B) largest when the external force is applied to the larger mass.
C) the same whether the external force is applied to the smaller or larger mass.
D) zero in all cases.

Question

Quizplus · Accepted Answer

When the external force is applied to the smaller mass, it has to accelerate both masses, requiring a larger contact force between them to accelerate the larger mass. When the force is applied to the larger mass, the required contact force to accelerate the smaller mass is less due to the smaller mass's lower inertia.

A Small Mass and a Large Mass Are in Contact