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Differentiation of potential energy

  • Thread starter zcabral
  • Start date
30
0
1. 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.)

2. Homework Equations

F=-dU/dx
U is potential energy

3. The Attempt at a Solution

i figured out the antiderivative of U(r) is -(A)/(3*r^(3)) but it isnt 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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Answers and Replies

21
0
you actually want the partial derivative of r
 
30
0
ok but how do u get that? im rather new at the whole calculus thing. wud it just b A/3r^3?
 
1,341
3
Think of U(r) as A*(r^-4) then try to differentiate it...
 

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