
#1
May1512, 09:33 PM

P: 1

In my experiment based on the inertia the angular velocity or speed goes either up or down with the angular momentum remaining the same. I understand that when a person is rotating to change the inertia you would either extend or detract the arms and legs (think dancer). I understand this concept and even somewhat how the calculate it except my angular momentum.
L=Iw since my inertia is changing how do I find the changing w(angular momentum) if I don't know the value of the L(angular momentum) yet. Would I just physically count the number of rotations per second in radians for each time the inertia is changed? 



#2
May1612, 06:22 AM

P: 16

Hi welcome to phy forum(everyone does that so i did it too for your first post)
Well you dont know the L now but i hope that you know the speed at which the dancer is expanding her/his arms(& her mass and her arms mass....etc). So you will calculate L(t) as a function output of time and you must know both L & w at some instant (maybe before after she moves her arms)simultaneously, this way you will know w(t). NOOOOOOOO! dont count the number of rotation per second, I have no grudge over counting but it will give an average w over a time of 1 sec, which will be hazardous if w is not constant. 



#3
May1612, 06:32 AM

Sci Advisor
HW Helper
Thanks
P: 26,167

himassb! welcome to pf!
the only convenient way i can think of is to transfer all the angular momentum to a "reference" body what exactly is your experimental setup? 


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