Question

1. a 20 kg box rests on a table.

a. identify the three action - reaction force pairs involved in the box sitting on the table.
the first pair is box - pair gravitational force pair. the second pair is box - table normal force pair
the third pair is table - earth force pair
b. what force does the earth exert on the box?
the formula for gravitational force is f = mg, m = 20kg and g = 9.8 m/s^2
f = mg = 20kg x 9.8m/s^2 = 196n
c. what force does the box exert on the earth?
the force of the box on the earth is equal in magnitude and opposite in direction to the force of the earth on
the box
d. what force does the table exert on the box?

Explanation:

Step1: Analyze the forces

According to Newton's third law, for every action, there is an equal and opposite reaction. When the box is on the table, the forces at play are gravitational and normal forces.

Step2: Calculate the normal force

Since the box is at rest, the normal force \(N\) exerted by the table on the box is equal in magnitude and opposite in direction to the gravitational force \(F_g\) acting on the box. The gravitational force \(F_g=mg\), where \(m = 20\space kg\) and \(g=9.8\space m/s^{2}\). So \(F_g=20\times9.8 = 196\space N\). Therefore, the normal force \(N = 196\space N\)

Answer:

The table exerts a normal force of \(196\space N\) on the box.