Differentiation of potential energy

AI Thread Summary
To find the radial force between two particles with potential energy U(r) = A/r^4, the force is calculated using F = -dU/dr. The correct derivative of U(r) leads to F = 4A/r^5, not the antiderivative previously mentioned. The confusion arises from misunderstanding the differentiation process; it is not necessary to divide U(r) by 2 since the force acts on each particle equally. A proper application of calculus is essential for accurate results. Understanding the differentiation of potential energy is crucial for solving problems involving forces in physics.
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Homework Statement



The potential energy of a system of two particles separated by a distance r is given by U(r) = (A)/(r^4), where A is a constant. Find the radial force that each particle exerts on the other. (Use A and r as appropriate in your equation.)

Homework Equations



F=-dU/dx
U is potential energy

The Attempt at a Solution



i figured out the antiderivative of U(r) is -(A)/(3*r^(3)) but it isn't the correct answer.
what else do u need to do besides the antiderivative which is equal to force. since it is 2 particles should i divide the U(r) funciton by 2?
 
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you actually want the partial derivative of r
 
ok but how do u get that? I am rather new at the whole calculus thing. wud it just b A/3r^3?
 
Think of U(r) as A*(r^-4) then try to differentiate it...
 

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