Calculating Angular Velocity and Energy Loss in a System of Two Rotating Discs

Join the discussion
Registration is free. Start your own thread to ask a follow-up.
2 replies · 4K views
Science Advisor
Gold Member
Messages
4,662
Reaction score
372
a disc with moment of inertia I1 turns around its axis which passes through its centre with an angular velocity of w0. we attach to it another disc with moment of inertia I2 (at first it doesn't spin), as a result of friction between the discs they achieve a combined angular velocity of w.
i need to find the combined angular velocity, w?
how much mechanical velocity was lost in the process.

basically i think i need to use here conversion of angular momentum, i.e the a.m before is I1w0, my problem is what the angular momentum after we add the second disc, i think it's I2w+I1w am i correct here?
if so then I1w0=(I1+I2)w.
and to calculate the loss of energy we have:
1/2I1w0^2-1/2(I1+I2)w^2, right?
 
Last edited:
Physics news on Phys.org
Assuming they rotate about the same axis, yes you are correct.