From what i read:
Normal force is the force that prevents objects from passing through eachother,which is the force of the repulsion from the charge.
The normal force will get as large as required to prevent objects from penetrating each other.
My question is about the scenario of a person inside an elevator:
The elevator has a mass of $1000kg$ and the person has a mass of $10kg$
At the first few seconds the variables are($_e$ is for "elevator" and $_p$ is for "person", i'm assuming that the acceleration due to gravity is $-10m/s^2$, "-" is for downward):
$v_e$ = $0m/s$
$a_e$ = $0m/s^2$
$v_p$ = $0m/s$
$a_p$ = $0m/s^2$
And the forces are:
The force of gravity on the elevator $f_g(elevator)=m_e*-10/s^2$
The force of gravity on the person $f_g(person)=m_p*-10m/s^2$
The force of the wire keeping the elevator in place(without considering the weight of the person becuase that's one of my questions) $f_w = +f_g(elevator)$
Now, there's a force of gravity applied on the person which is $f_g=10kg*-10m/s^2=-100n$
So the person is supposed to accelerate downward,but it can't go through the elevator becuase of the normal force which I said what I think it does at the start of the question
Here's what I think is happening:
If the normal force were to be applied on the elevator by the person's feet, then it would be greater than if it were to be applied on the person's feet by the elevator(becuase the mass of the person would require less force for the elevator to stop it,than the mass of the elevator would require for the person to get the elevator moving with her/him so she/he doesn't penetrate the elevator)
Therefore the normal force is applied on the person by the elevator (as small as it can be) for them to not penetrate eachother, $f_n=f_g(person)$
When there is a net force on the elevator which accelerates it upward,the normal force is applied on the person by the elevator to prevent them from penetrating eachother because that way it is less than if the normal force were applied on the elevator by the person(becuase the mass of the person would require less force for the elevator to get the person moving with it,than the mass of the elevator would require for the person to get the elevator to stop,so they don't penetrate).
And the normal force in that case is $f_n=m_p*(a_g+a_e)$ applied on the person by the elevator.
The main thing:
- IlIs my interpretation of normal force correct??,or does the normal force have to be applied on the "moving" object??
- I heard a lot that when the elevator starts decelerating(acclerating in the downward direction) the elevator would apply a normal force on the person which is as small as it can be to prevent her/him from penetrating the elevator,and because the elevator is decelerating,the force will be less than gravity(assuming that the person has the velocity of the elevator before it was decelerating)
But if the elevator is slowing down(the same goes if the velocity was negative), that means for sometime the person wouldn't be in contact with the elevator(because the person's velocity has to be the same as the elevator's for her/him to not penetrate the elevator,the elevator has to change its velocity first before the velocity of the person can change due to gravity's downward accleration)
So how can there be a normal force applied??
- Does normal force come in pairs?? and if it does, in what way??
If not,what is the opposite and equal force to the normal force??
I tried to make my question as clear as possible.......(: