Moment of Inertia for a circular platform system

[fatfatfat]

I need to know how to figure out the moment of inertia of a system that consists of a spinning circular platform with a student standing still on the platform.

I figure that it would just be the sum of the moments of intertia of the platform and the student. I can figure out the platform's moment of intertia easy enough, but I'm not sure how to figure out that of the student.

...

Or am I headed in the wrong direction?

Any help will be appreciated :)

 

[marlon]

Well, normally such problems involve the conservation of angular momentum law (hence, the addition is correct) and either the angular momentum of the guy is given or you just call it L' but you won't really need to know the exact value to solve the problem.

What exactly is the problem you are trying to solve ?

marlon

 

[Doc Al]

I figure that it would just be the sum of the moments of intertia of the platform and the student.

Absolutely.

I can figure out the platform's moment of intertia easy enough, but I'm not sure how to figure out that of the student.

Treat the student as a point mass. What's the moment of inertia of a point mass about some axis?

 

[fatfatfat]

Yeah, it is a question about the conservation of angular momentum haha... and yeah, I read a question that was almost the same as mine somewhere else on the forums and it talked about point mass, but I don't think our teacher has discussed that yet. I don't know how to find the moment of inertia for one, I don't think. Maybe I know it and I just can't think tonight! haha. I don't know.

 

[Doc Al]

Read this: http://hyperphysics.phy-astr.gsu.edu/hbase/mi.html#mig"

 

[fatfatfat]

Thank you!