- #1
seang
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Homework Statement
Sorry for wasting your time and bandwidth, but I can't figure this out. I just have a cantilever beam with the following specifications:
length : 40 in.
width: 2 in.
height: 2 in.
E = 30e6 psi.
mbar = .8991 lbm/in.
And I'm trying to find the beam's resonance frequency (first mode). The problem is, I can't get a consistent answer between using SI units and the disastrous units given above.
Homework Equations
First I converted all of the above values to SI:
length = 1.016 m
width = .0508 m
height = .0508 m
E = 2.068e11 Pa
mbar = 15.878 kg/m
And I'm using the equation below to calculate the resonance frequency.
[tex]\omega = (1.875)^2 \sqrt{\frac{EI}{\overline{m}l^4}[/tex]}}
where
[tex]I = \frac{wh^3}{12}[/tex]
The Attempt at a Solution
If i do this, I get about 14.74 Hz for the imperial figures, and 289.6 Hz for the SI case. What gives? I have to be doing something wrong...
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