A mass sits at rest on top of a table. Which two forces that are not action-reaction partners are equal and opposite?
A) the force of gravity on the mass due to the Earth and the force of gravity on the Earth due to the mass
B) the contact force on the mass due to the table and the contact force on the table due to the mass
C) the force of gravity on the mass due to the Earth and the contact force on the table due to the mass
D) the force of gravity on the mass due to the Earth and the contact force on the mass due to the table
E) the contact force on the mass due to the table and the force of gravity on the Earth due to the mass

Question

Quizplus · Accepted Answer

The force of gravity on the mass due to the Earth and the contact force on the mass due to the table are equal and opposite. This is because the gravitational force pulling the mass downward is balanced by the normal force (contact force) from the table pushing the mass upward, allowing the mass to remain at rest on the table. These forces are not action-reaction pairs because they act on the same object (the mass).

A Mass Sits at Rest on Top of a Table