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## Homework Statement

"A rod of mass 4.0 kg and length 1.5 m hangs from a hinge. The end of the rod is then given a 'kick' so that it is moving at a speed of 5 m/s. How high will the rod swing? Express you answer in terms of the angle the rod makes with the vertical.

## Homework Equations

KE(rot) = 0.5Iw

^{2}

I(rod, pivot at end) = (1/3)mL

^{2}

w = v/r

h = L-Lcosθ

## The Attempt at a Solution

I have tried many, all yielding the incorrect answer. Posted solutions (answers only, no work shown) says that θ=64°

KE

_{o}= PE

_{f}

0.5mv

^{2}= mgh

0.5mv

^{2}= mg(L-Lcosθ)

This yields an answer of 81.39°

If I do:

0.5mv

^{2}+ 0.5Iw

^{2}= mgh

" + " = mg(L-Lcosθ)

this also results in an incorrect answer. I don't remember what it was.

If:

0.5Iw

^{2}= mgh → (mg(L-Lcosθ))

This one gives me θ=44.23°

I've spent 9 hours on 10 homework problems, and have 3 finished. Please help me.