- #1

aa_o

- 24

- 4

## Homework Statement

## Homework Equations

## The Attempt at a Solution

The moment of inertia before collapse is for each rod:

BEFORE COLLAPSE:[/B]

I

_{b}= ∫(L

^{2}+ x

^{2}) dm = m/L ∫(L

^{2}+ x

^{2}) dx = 4/3 * m * L

^{2}

We have 8 of these plus the inertia of the mechanism, giving a total I,

I

_{t}= 8 * I

_{b}+ I

_{k}= (32/3 * m * + 40/3 * M) * L^2

The energy is thus:

T

_{b}= 1/2 * I

_{t}* ω

_{o}

^{2}

**AFTER COLLAPSE:**

I

_{a}= ∫(x

^{2}) dm = m/L ∫(x

^{2}) dx = 1/3 * m * L

^{2}

And the mechanism is the same:

So we have total of:

I

_{t_a}= 8 * I

_{a}+ I

_{k}= (8/3 * m * + 40/3 * M) * L

^{2}

The energy is now:

T

_{a}= 1/2 * I

_{t_a}* ω

_{o}

^{2}

And energy difference must be:

T

_{a}- T

_{b}= 1/2 * ω

_{o}

^{2}* m * (8 / 3 - 32/3) * L

^{2}= -ω

_{o}

^{2}* m * 4 * L

^{2}

But the solution stated is: ω

_{o}

^{2}* M * 6 (note the difference in mass symbol)

What am i doing wrong?

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