What is the Force Exerted by a Heated Steel Beam with Clamped Ends?

[Punkyc7]

Homework Statement

Suppose the ends of a 20-m-long steel beam are rigidly clamped at 0°C to prevent expansion. The rail has a cross-sectional area of 30 cm^2. What force does the beam exert when it is heated to 40°C? ( αsteel = 1.1 × 10−5/C°, Ysteel = 2.0 × 1011 N/m2).

Homework Equations

delta L =alpha Li delta T

The Attempt at a Solution

I solve for the new length and get 20.0088m. I don't know what Ysteel is used for or were to start after finding the new lenght.

 

[Punkyc7]

The answer is one of these if that helps
a. 2.6 × 105 N
b. 5.6 × 104 N
c. 1.3 × 103 N
d. 6.5 × 102 N
e. 2.5 × 102 N

 

[Mapes]

Do you know what the Young's elastic modulus Y signifies and how to work with it? If so, how much stress (and then, how much force) is required to compress the length back to 20 m?

 

[Punkyc7]

no i haven't seen it before, what is the equation?

 

[Mapes]

You might want to read http://en.wikipedia.org/wiki/Young%27s_modulus" .

 

[Punkyc7]

thanks i got it now