# Homework Help: Deflection cantilever beam

1. Oct 11, 2013

### raymanmusic

1. The problem statement, all variables and given/known data
How do I find an expression for the deflection at midspan for a cantilever beam loaded with a uniformly distributed load?

Illustration of beam: http://goo.gl/3SxeVZ [Broken]

2. Relevant equations
$\delta = \frac{Qx^2}{24EI}(6L^2-4Lx+x^2)$

3. The attempt at a solution
Attempt at solution: http://goo.gl/umUBkU [Broken]

My current answer is: $\frac{49QL^4}{1280EI}$, I think this is wrong. Putting $x = \frac{L}{2}$ in the elastic curve formula I get: $\frac{17QL^4}{384EI}$, I think this is the correct answer.

Last edited by a moderator: May 6, 2017
2. Oct 11, 2013

### SteamKing

Staff Emeritus
You can always check your formula for the deflection by setting x = L and seeing if your result is the same as that from a beam table.

3. Oct 13, 2013

### nvn

raymanmusic: qx = q, not qx = q*x/L. Try again.

4. Oct 14, 2013

### raymanmusic

Yes, that was the mistake. I got the correct answer now: $\frac{17QL^4}{384EI}$. Thank you nvn.