# TOUGH QUESTION: Rotational Kinematics

#### cheechnchong

MY Question was answered!! thanks to those who posted...i got the right answer from the book!!

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#### Hootenanny

Staff Emeritus
Gold Member
HINT: To create the artificial gravitational force what must the centripetal acceleration of the space station be? How fast must the station be rotating to achieve this centripetal acceleration?

#### cheechnchong

Hootenanny said:
HINT: To create the artificial gravitational force what must the centripetal acceleration of the space station be? How fast must the station be rotating to achieve this centripetal acceleration?
ohhhhhhhhh good one

#### OlderDan

Homework Helper
Hootenanny said:
HINT: To create the artificial gravitational force what must the centripetal acceleration of the space station be? How fast must the station be rotating to achieve this centripetal acceleration?
Why do you need to know anything about the centripetal acceleration? The artificial gravity would not have to be the same as earth's gravity.

#### Hootenanny

Staff Emeritus
Gold Member
OlderDan said:
Why do you need to know anything about the centripetal acceleration? The artificial gravity would not have to be the same as earth's gravity.
Indeed, I was wrong. This should be treated as a conservation of angular momentum problem. Good Catch Dan, apologies to chee.

#### cheechnchong

Hootenanny said:
Indeed, I was wrong. This should be treated as a conservation of angular momentum problem. Good Catch Dan, apologies to chee.
ok but how do i discern the what the masses are used for?? is the angular moment L = Iw ?

#### Office_Shredder

Staff Emeritus
Gold Member
You know what I is initally. You should be able to figure out what I is if everyone is in the center. You should also be able to figure out what I is if everyone is on the outer shell.

You know Iw is constant (angular momentum is constant), so put I when everyone is in the middle over I when everyone is on the outside, you get w when everyone is on the outside over w when everyone is inside

#### cheechnchong

Office_Shredder said:
You know what I is initally. You should be able to figure out what I is if everyone is in the center. You should also be able to figure out what I is if everyone is on the outer shell.

You know Iw is constant (angular momentum is constant), so put I when everyone is in the middle over I when everyone is on the outside, you get w when everyone is on the outside over w when everyone is inside
this is extremely clear...will try this when i get home later today! thanks and if have any probs check your PM...if you choose to

#### cheechnchong

Hootenanny said:
Indeed, I was wrong. This should be treated as a conservation of angular momentum problem. Good Catch Dan, apologies to chee.
hey it's fine! no worries

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