Question #3e069

2 Answers
Feb 21, 2018

#100# N

Explanation:

This is actually a question which can befool students.

Newton's Third Law says,

The Action and Reaction are equal in magnitude and act on opposite directions.

So, #F_(1->2) = -F_(2->1)#

So, If the Students exerts #100# N , the desk will also exert #100# N. (The minus sign indicates direction relative to the initial force, so don't be confused.)

Hope this helps

Feb 21, 2018

#-100N#

Explanation:

Newton's third law of motion states that

Every action has an equal and an opposite reaction

It doesn't matter what is the student's mass or the desk's mass, the only thing that matters is how much force he/she exerts on the desk.

Since they exert #100N# on the desk, then desk will also exert #100N# on them in return, but only in the opposite direction, so physicists write it as negative force, and in this case it'll be #-100N#.