Ludo doesn't believe in cheating on school work, but then he took a french test and everyone else was cheating, so he did it, too. now, he tells himself that cheating is usually bad, but sometimes it is o. k. this is an example of:

The correct answer is ''Cognitive Dissonance''.

Explanation:

The Cognitive Dissonance is the name given to the psychological term that refers to the mental discomfort, or psychological stress that an individual has when he holds two or more contradictorial beliefs, ideas or values. It all starts when the person experience a situation where his beliefs are put in risk due to a new evidence perceived by the person that began to question his previous way to see things.

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.