Homework Help: Spring physics help

1. Nov 13, 2006

ponjavic

More vibrations woho.

The mass (top) can only move vertically. the two bars are weightless. The springs are bottom left = 100N/m bottom middle = 100 bottom right = 300.

They are symmetric away from the bars.

So what I did was make the two on the bottom left into one as 100+100 = 200.

Then they are now in parallel with the one above. 1/k=1/200+1/200 which yields the whole left side = 100.

Now replace the 2 ones left with (100+300)/2 and voila k for the whole system = 200. Probably wrong.

The mass of the block is 1 kg. wn=root(k/m) and I get 14 something I think it is hz?

Answer is 2.76 Hz, what do I need to do?

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2. Nov 14, 2006

lax

I did not check your calculation as figure is not clear for me.
But SQRT(k/m) is for Angular Velocity.
For Frequency (f) which is in Hz you need to divide it by 1/(2*3.14)
If you send me the figure, I can work it out.

3. Nov 21, 2006

ponjavic

hmm that gives me 2.25 hz, so I guess the k should be higher. I'll draw a better figure now

Maybe that helps?

And the top left spring is 200!

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Last edited: Nov 21, 2006
4. Nov 22, 2006

lax

Can you pl. check your Spring constants values.
Because if resultant spring constant becomes 300, then you get frequency as 2.76 Hz.
But with present values you supplied it's not possible.
Sorry for that.