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Gamerex
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Homework Statement
Let's say I'm holding a crate up against the ceiling with a force of 'P', and the crate is stationary.
What is the normal force?
Homework Equations
Newton's 1st law: ƩF=0
The Attempt at a Solution
I have three forces acting on the crate - The normal force, the gravitational force, and the applied force.
According to Newton's first law, Fg+Fn+Fa=0
Thus, Fn=-Fg-Fa
Since Fg pulls down Fg=-mg
Since Fa pushes up, Fa=P
Thus, Fn=mg-P
However, my book says Fn=P-mg. What am I doing wrong?