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Forces between 2 protons

I know that the forces acting between 2 protons are:

Gravitational attractive force
Electrostatic repulsive force
Strong nuclear force

However, I am not sure what the relationship between these 3 forces is.

Is it Fs = Fg + Fe or Fs = Fe - Fg ?

Or are these the same, but the second one is considering the direction of the force whereas the first is only considering magnitude, since -(-) would give you an addition of the magnitudes of the two forces?
Reply 1
Original post by voltz
I know that the forces acting between 2 protons are:

Gravitational attractive force
Electrostatic repulsive force
Strong nuclear force

However, I am not sure what the relationship between these 3 forces is.

Is it Fs = Fg + Fe or Fs = Fe - Fg ?

Or are these the same, but the second one is considering the direction of the force whereas the first is only considering magnitude, since -(-) would give you an addition of the magnitudes of the two forces?


The strongest force is the strong, followed by the electrostatic, followed by gravity

In fact, Fs > Fe + Fg ( I am 99% sure of this)

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(edited 6 years ago)
Reply 2
Original post by Kyx
The strongest force is the strong, followed by the electrostatic, followed by gravity

In fact, Fs > Fe + Fg ( I am 99% sure of this)

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So the equation to use would be Fs = Fg + Fe? Its just that I came across a past paper question which uses Fe = Fg + Fs so I'm a but unsure.
Reply 3
Original post by voltz
So the equation to use would be Fs = Fg + Fe? Its just that I came across a past paper question which uses Fe = Fg + Fs so I'm a but unsure.


I think I get it now.

The protons experience no net force, so Fe = Fs + Fg

Therefore Fs = Fe - Fg

Do you know the answer to the question?


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Reply 4
Original post by Kyx
I think I get it now.

The protons experience no net force, so Fe = Fs + Fg

Therefore Fs = Fe - Fg

Do you know the answer to the question?


Posted from TSR Mobile


Yes, the answer is Fs = Fe - Fg.

Would you not get the same answer if you used Fs = Fe + Fg but ignored the minus sign on the gravitational force? So adding the magnitudes?
(i) Complete Fig for the time until the ball reaches B.Physics 9702 Doubts   Help Page 102   Physics Reference.png Im new dont know where to get an answer hope someone helps.
Reply 6
Original post by voltz
Yes, the answer is Fs = Fe - Fg.

Would you not get the same answer if you used Fs = Fe + Fg but ignored the minus sign on the gravitational force? So adding the magnitudes?


I do not know :frown:


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