# Homework Help: Moment for bending materials test

1. Oct 4, 2012

### scotty03

1. The problem statement, all variables and given/known data
I have to do the following practical, but I am unsure of how to calculate one of the variables.

We are doing this test

and we are given this information to calculate E.

I have equations on how to calculate R and I, but I am not sure how to calculate M. It's obviously something to do with the mass of the weights on the end and the distance from them, but this information isn't included in the prac sheet.

Does anyone have any ideas?

2. Oct 4, 2012

### pongo38

In the 400 mm length, M is constant. Are you able to calculate the reactions, where the little triangles are?

3. Oct 4, 2012

### scotty03

They both = W from sum of forces in Y direction.

The idea of the test was to see how much the material deflected upwards in the middle. I am just not sure if the applied moment is W*100mm or W*100mm*2 or W*300 or W*300*2

4. Oct 4, 2012

### pongo38

One definition of Moment at a section is: The sum of the moments on one side (or the other) of the section. So, at the point of application of the load at the end, you should find the moment is zero. In the central section it is W*300. You should check this by considering a section distance x from the left hand support, going to the right.