# Calculating work using hookes law

1. Jan 13, 2010

### dw10

1. The problem statement, all variables and given/known data
Calculate the work done, in Joules for a system in which a muscle of 1cm^2 cross section and 10cm length is stretched to 11cm by hanging a mass on it. The muscle behaves like a spring. The spring constant for the muscle was determined by finding that the muscle exerts a force of 5.00N when it is stretched from 10.0cm to 10.5cm

2. Relevant equations
Is spring constant (-k) calculated simply by dividing .005m into 5.00N? (because F= -kx, and -k = F/x) = -1000.

3. The attempt at a solution

i dont think my answer will be correct because i have a feeling that im calculating k incorrectly??
OK so assuming Im doing it right though...

i set up the integral using hookes law:

|work| = int (from .10m to .11m) -k (x - x0)dx

= int (from .10m to .11m) -1000 (x - x0)dx
then i took constants out of integral and integrated...

|work| = -1000/2 * |from .10m to .11m [ (xf-x0)^2 - (xi - x0)^2]

i dont want to proceed further unless i am on right track (which i doubt) thanks for any help!
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Jan 13, 2010

### Dick

Right. k=1000*kg/s^2. Put units on the these numbers, ok? They aren't dimensionless. Now continue with the second part.

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