# Homework Help: Picking a chain from one end

1. Oct 10, 2008

### imranq

1. The problem statement, all variables and given/known data
You have a chain of length 10m with 80kg, how much work does it take to lift this chain from one end to 6ft?

2. Relevant equations

$$\delta = \frac{10}{80} = .125$$

3. The attempt at a solution

$$W = \int{F(x)}\,dx = \int^{6}_{0}{\delta lg}\,dl = \frac{\delta l^2g}{2}$$

I dont think that is right though

2. Oct 10, 2008

### Redbelly98

Staff Emeritus
So far so good, you just need to evaluate the integrated expression at the integral's limits.

Is it 6 ft or 6 m?

3. Oct 10, 2008

### imranq

Oh whoops! Everything that denotes length is in feet

4. Oct 10, 2008

### Redbelly98

Staff Emeritus
Okay. I'm wondering about the "kg" too then.

5. Oct 10, 2008

### imranq

I don't really remember the problem so well. But the inherent integral should be the same, no? Unless you refer to lbs as weight or something.

6. Oct 10, 2008

### Redbelly98

Staff Emeritus
Yes, the inherent integral is the same. Using lbs can get a little confusing since lbs are a force unit, not mass.