# Change in length (young)

1. Apr 20, 2013

### Jbreezy

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

A marble column with cross sectional area of 45cm^2 supports a load of 8.5 x 10^4 Newtons.
The marble has a Young's modulus of 5.5 x 10^10 N/m^2 and a compressive strength of 1.8 x 10^8 Pa. If the column is 2.75m high, what is the change in length of the column?

2. Relevant equations
Y(ΔL/L) = F/A

Where Y is young modulus.
3. The attempt at a solution

Y(ΔL/L) = F/A
Solve the equation for ΔL and you get.
ΔL = (FL)/ (AY)
So plugging in the values you get.
ΔL = ((8.5 x 10^4 N)(2.75m)) / ((.45m^2)(5.5 x 10^10 N/m^2))
So ΔL = 9.44 x 10^-6
Can someone double check me? I don't understand why my instructor gave me this number
1.8 x 10^8 Pa.

2. Apr 20, 2013

### Staff: Mentor

45cm^2 is not .45m^2.
Maybe to check if the column breaks down.

3. Apr 20, 2013

### Jbreezy

OK. So with that correction

ΔL = ((8.5 x 10^4 N)(2.75m)) / ((0.0045 m^2)(5.5 x 10^10 N/m^2))
So ΔL = 9.44 x 10^-4

Is this correct now? Thanks for the help.

4. Apr 20, 2013