# Calculate the angular momentum of a solid uniform sphere

1. Nov 11, 2009

### raiderIV

1. The problem statement, all variables and given/known data
Calculate the angular momentum of a solid uniform sphere with a radius of 0.120m and a mass of 14.0kg if it is rotating at 6.00rad/s about an axis through its center.

2. Relevant equations
Angular Momentum = I * w

3. The attempt at a solution
When using the formulas above i am obtaining the answer 0.1008 however, that is not the correct answer. Any Ideas?

Edit: I also know that the answer needs to be in kg * m2/s

2. Nov 11, 2009

### stanton

always take a careful look at question and gather all the information and equations you know to solve this problem. Maybe you can change a little bit of equations or connect them together and you will get it.
L = I*ω
Plug values given:
0.5mr²*ω = 0.5*14*.12²*6.00= ____ kg∙m^2/s
yup. looks good to me! hope this helps.
And by the way, just guessing, do you also need to calculate the KE for that?

Last edited: Nov 11, 2009
3. Nov 11, 2009

### raiderIV

Yup... I see what i did wrong... in every calculation i did i was thinking cylinder for I instead of sphere. Thank you. And yes I do have to find the KE which turns out to be 1.45J

Thanks again for the help,
~John

4. Nov 11, 2009

### stanton

Wait. I revised my answer because there were some error. Please refer to that. Sorry about that...
[0.5mr²*ω = 0.5*14*.12²*6.00= ____ kg∙m^2/s
This is right. I calculated 0.4 instead of 0.5

5. Nov 11, 2009

### raiderIV

Your first answer was correct because the moment of inertia for a sphere is 2/5mr2

So you did it correctly, and thanks again ^_^