After watching and reading many explanations on friction, normal force and newton's laws, I am more confused than I was before... I have a simple question:
- Why is the normal force of an object that is moved across a horizontal plane equal to the applied force when the velocity is constant?
First, I thought the normal force is not equal to the applied force but to the force of the weight which points downward in a body diagram. But then I figured this can't always be true because the normal force of inclined surfaces is not directly opposite to the force of the weight. But I don't understand why the normal force should be equal to the friction force. The Force of friction is $F = \mu.mg$ ($\mu$ = friction, $m$ = mass, $g$ = gravity), right? And this is the same as saying the Force of friction is the same as the applied force, right? - But what is the formula of the normal force in this case?
How can I proof mathematically that the $Fapplied = Fnormal$?
I always read the friction force is proportional to the normal force but why?
It seems like nobody can give me a simple explanation why this is true.