# A thin uniform bar, hanging, is hit by a ball. Find the angular velocity

1. Dec 4, 2012

### Phys121VIU

1. The problem statement, all variables and given/known data
A thin, uniform metal bar, 3m long and weighing 75N, is hanging veritcally from the ceiling by a frictionless pivot. Suddenly it is struck 1.3m below the ceiling by a small 2 kg clay ball, initially travelling horizontally at 14m/s. The ball sticks to the bar

Find the angular velocity of the ball+bar just after the collision.

2. Relevant equations
3. The attempt at a solution

Angular momentum is conserved so my understanding is that

Angular momentum of the ball = angular momentum of the bar and bar

Lball = (Ibar + Iball2

(2kg)(14m/s)(1.3m) = [(1/3)(75N/9.8m/s2)(3m)2 + (2kg)(1.3m)22

so i worked it out and got ω = 1.18 rad/s

but thats not correct...I cant think of any other way to approach it
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Dec 5, 2012

### ehild

Are you sure that the last formula is correct?

ehild

3. Dec 5, 2012

### Phys121VIU

Wow..its definately not squared..thanks:P