# Force and potential energy function

1. Oct 6, 2012

### bdh2991

1. The problem statement, all variables and given/known data

A single conservative force acting on a particle within a system varies as = (− Ax + Bx5) N, where A and B are constants, is in newtons, and x is in meters.

(a) Calculate the potential energy function U(x) associated with this force, taking U = 0 at x = 0. (Use any variable or symbol stated above as necessary.)
U(x) =

(b) Find the change in potential energy and change in kinetic energy as the particle moves from x = 1.90 m to x = 3.80 m. (Use any variable or symbol stated above as necessary.)

2. Relevant equations

F = -∇U

3. The attempt at a solution

for part a i took the partial derivative with respect to x in order to get the potential energy function in which i got the answer: U(x) = (A - 5Bx^4)i the system said it was wrong though.

for part b i took my equation in part a to find the change in potential energy and got -977J
and i figured if the change in potential was lost 977 J then the change in kinetic energy would have to be gaining 977 Joules, but i was wrong again. please help

2. Oct 6, 2012

### bdh2991

Nvm i was doing it backwards and should have been integrating sorry guys

3. Mar 3, 2013

### SEATTLE7384

what was the answer

what was the answer to part A

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