A 4-kg mass and a 5-kg mass are in contact with each other while resting on a smooth table. A 20-N external force is applied to the 4-kg mass (in a direction toward the 5-kg mass). The contact force between the two masses is
A) 20 N.
B) 9 N.
C) 0 N.
D) 11 N.

Question

Quizplus · Accepted Answer

The total mass is 9 kg, and the acceleration is 20 N / 9 kg = 2.22 m/s². The contact force on the 5-kg mass is 5 kg * 2.22 m/s² = 11.1 N, approximately 11 N.

A 4-Kg Mass and a 5-Kg Mass Are in Contact