Calculate angular momentum? I almost got the right answer but it's wrong Help

[riseofphoenix]

Calculate angular momentum? I almost got the right answer but it's wrong! Help!

This is what I did for part a...

1. What is given

Particle
m_p = 0.450 kg
ω = 2.00 rad/s
r = 1 m

Stick
m_s = 0.125 kg
ω = 2.00 rad/s
r = 0.5 m

2. Angular momentum is conserved (L_initial = L_final) due to a lack of friction

0 = L_final

L = Iω
L = (mr²)ω
L = (0.450 + 0.125)(0.5²)(2)
L = (0.575)(0.25)(2)
L = 0.2875

Help!

 

[Spinnor]

The formula you use for I is only good for a point mass. For a distributed mass (the meter stick) you must use a different formula, see,

http://www.physics.uoguelph.ca/tutorials/torque/Q.torque.inertia.html

and use the appropriate formulas for the slender rod.

So I_total = I_meter stick + I_mass

 

[TSny]

2. Angular momentum is conserved (L_initial = L_final) due to a lack of friction

0 = L_final

?? This problem does not involve conservation of angular momentum.

L = Iω
L = (mr²)ω

You need to find the moment of inertia of the stick either by calculation using calculus or by consulting a table.