Young's modulus of a steel post, finding change in length

[DracoMalfoy]

Homework Statement

Superman pulls on a steel post to trap a supervillian. The post has a cross-sectional area of 30cm^2 and a length of 2m. If Superman applies a force of 6X10^6N by how much is the length of the post increased?

A) 2mm

B) 7mm

C) 1.2cm

D) 1.7cm

E) 2cm

Homework Equations

F/A= Y(of steel post) ⋅ΔL/Li

F= 6x10^6N
A=30cm^2= .3m^2
Li=2m[/B]

The Attempt at a Solution

[/B]
I know I'm supposed to find the change in length, but when I use this equation, I'm getting 1.9 which isn't an answer choice. I'm not sure what I'm doing wrong here.

 

[stockzahn]

Homework Statement

Superman pulls on a steel post to trap a supervillian. The post has a cross-sectional area of 30cm^2 and a length of 2m. If Superman applies a force of 6X10^6N by how much is the length of the post increased?

A) 2mm

B) 7mm

C) 1.2cm

D) 1.7cm

E) 2cm

Homework Equations

F/A= Y(of steel post) ⋅ΔL/Li

F= 6x10^6N
A=30cm^2= .3m^2
Li=2m[/B]

The Attempt at a Solution

[/B]
I know I'm supposed to find the change in length, but when I use this equation, I'm getting 1.9 which isn't an answer choice. I'm not sure what I'm doing wrong here.

I also obtain 19 mm. But if I use 200000 N/mm^2 instead of 210000 N/mm^2, the calculation yields 2 cm exactely. Maybe it was rounded down ...