(adsbygoogle = window.adsbygoogle || []).push({}); Youngs modulus of a cantilever, help please!!

[1] BACKGROUND:

I am doing an experiment determining the young's modulus of a cantilever through principles of SHM (i.e. hypothesis: higher youngs modulus = higher frequency of oscillation.

See the attached Pictures for the diagram (strobe is used to find frequency of cantilever with use of beat frequencies).

We were given the attached formula to manipulate to find young's modulus.

T=Period of oscillation

M=Load at end of cantilever (Forget about mass of cantilever, negligible)

L=Length between cantilever's fixed pivot and the load's centre of mass

E=Youngs Modulus

I=Moment of Inertia

[2] Problem:

I have done everything a thousand times over, and i consistently get a value of 15Gpa for youngs modulus! isnt that far too high for a classroom wooden ruler?

I have used SI units and everything has been done right, the only thing i can think of is the formula is wrong is the formula we were given is flawed.

I personally think the problem lies in the moment of inertia sub-formula, I was given bd^{3}, where b= width of beam d=depth of beam.

I dont know ANYHTING about moments of inertia, but surely that is wrong?? That would mean if the beam was 10cm or 10000km long, the moment of inertia would be equal.

I know its asking alot but please help, this is my final report and I'm pretty screwed.

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Youngs modulus of a cantilever, help please

**Physics Forums | Science Articles, Homework Help, Discussion**