1. Jan 16, 2010

### kavamo

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

A 0.46 m long guitar string, of cross-sectional area 1.1 10-6 m2, has Young's modulus Y = 2.20 109 N/m2. By how much must you stretch the string to obtain a tension of 10 N?

2. Relevant equations

???

3. The attempt at a solution

I don't know how to begin this problem. What is Young's modulus, and how is it used?
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Jan 16, 2010

### payumooli

youngs modulus is the ratio of stress to strain

stress is given in force/unit area

strain change in dimension/original dimension (no units)

all values are given except change in dimension

3. Jan 16, 2010

### kavamo

so do I use hooks law?

F/A=Y delta L/L

I got it! The answer is 1.9 mm.

Thanks!

Last edited: Jan 16, 2010
4. Jan 16, 2010

### RoyalCat

Yep. That's using the definition of Young's Modulus!

Isolate your unknown variable, $$\Delta \ell$$ as a function of all your known variables, $$F, A, \ell, Y$$ and just stick all the values into the formula you get.