A small 13.0-g bug stands at one end of a thin uniform bar that is initially at rest on a smooth horizontal table. The other end of the bar pivots about a nail driven into the table and can rotate freely, without friction. The bar has mass 70.0 g and is 90 cm in length. The bug jumps off in the horizontal direction, perpendicular to the bar, with a speed of 25.0 cm/s relative to the table.(adsbygoogle = window.adsbygoogle || []).push({});

1. The problem statement, all variables and given/known data

What is the angular speed of the bar just after the frisky insect leaps?

mass of bug = .013kg

mass of bar = .070kg

length of bar = 0.9m

final velocity of bug = 0.25 m/s

initial velocity of bug = 0

initial velocity of bar = 0

2. Relevant equations

I = (1/3)ML^2

K(bug) = (1/2)mV^2

K(bar) = (1/2)Iw

Sum of the energy before = sum of the energy after

3. The attempt at a solution

0 = K(bug) + K(bar)

0 = (1/2)mV^2 + (1/2)Iw

0 = (1/2)mV^2 + (1/2)(1/3)ML^2w

w = -[mV^2]/[(1/3)ML^2]

but that doesn't come out with the correct answer

where w is the lowercase omega standing for angular velocity

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# Homework Help: Conservationof energy and angular speed

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