How to explain there cannot be a case where r=0 in F=G(Mm/r^2)by WaaWaa Waa Tags: case, explain, fgmm or r2 

#1
Feb2413, 03:51 PM

P: 12

Hi. This is my first post here. In one of our science groups in Facebook, a member is asking about a case where r=0 in Newton's Equation F=G(Mm/r^2)
The best i could do was to state that there cannot be two point masses with a distance r=0 between them. He seems to accept my explanation but his intuition that it should be 'infinity' still remains. I would like to explain it better. Can you please help? I have searched the site but could not find the answer. If there is already a thread, I would be glad if you could point me towards it. 



#2
Feb2413, 04:25 PM

HW Helper
P: 6,210

The gravitational force of attraction between two point masses, M & m_{2}, separated by a distance 'r' is given by:
F= GMm/r^{2} If r=0, then you don't have two masses anymore but one mass. In which cases, gravity would vary with depth of the planet. Read more here. 



#3
Feb2413, 04:40 PM

P: 2





#4
Feb2513, 12:33 AM

P: 101

How to explain there cannot be a case where r=0 in F=G(Mm/r^2)
I don't think the gravity law works well on a quantum scale since the nuclear forces and electromagnetic forces become very strong at small distances.




#5
Feb2513, 01:29 AM

P: 12

Thank you guys for your insights, we managed to resolve the question.
When we are talking about classical physics, I think we sometimes tend to grab ideas from Relativity and Quantum Mechanics and get confused and this seems to be the root of the problem. 


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