- #1

HoodedFreak

- 30

- 0

## Homework Statement

A 500.0-g bird is flying horizontally at 2.25 m>s, not paying much attention, when it suddenly flies into a stationary vertical bar, hitting it 25.0 cm below the top(Fig. P10.85). The bar is uniform, 0.750 m long, has a mass of 1.50 kg, and is hinged at its base. The collision stuns the bird so that it just drops to the ground afterward (but soon recovers to fly happily away).What is the angular velocity of the bar (a) just after it is hit by the bird and (b) just as it reaches the ground?

## Homework Equations

L = Iw

L = p x r

I = ML^2/3 for a rod

## The Attempt at a Solution

a) The angular momentum before the collision:

L

_{1}= L

_{bird}+ L

_{rod}= p x r + 0 = mvr

Then afterwards:

L

_{2}= L

_{bird}+ L

_{rod}= 0 + Iw

we get the equation: mvr = Iw from conservation of momentum

Plug in the numbers: 0.5 * 2.25 * (0.75-0.25) = 1.5 * (0.75)^2 * w/3

Solve for w = 2 rads/s

b) I'm not really sure how to attack this one, the angular momentum won't be conserved because of the gravity enacting a torque on the object.

Any suggestions?