Help me find angular velocity and change in Kinetic Energy

AI Thread Summary
The discussion revolves around a physics problem involving two wheels merging and the need to find their final angular velocity and change in kinetic energy. Wheel A has an initial angular velocity of 35 rad/s and a moment of inertia of 25 kg*m², while Wheel B has a moment of inertia of 15 kg*m² and is assumed to start at rest. The conservation of angular momentum is emphasized as the key principle to solve for the final angular velocity after the wheels stick together. Participants suggest using the formula for kinetic energy, K.E. = 1/2 I ω², to calculate the initial and final kinetic energies. The discussion highlights the importance of correctly applying these principles to arrive at the solution.
samemikejones
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got a real tricky but fun problem, wheel A is going 35 rad/s, with I = 25 Kg*m2 and merges into wheel B with I = 15 Kg*m2, if they stick together at contact, find its angular velocity and change in Kinetic Energy...

PlEASE HELP:

So far, I have L = IW, or 8.8 x 10^2 kg m2/sec

and L = IW for oval to be at 9.8 x 10^2 kg m2/sec,

w = L/I
need some guidance from here...PLEASE HELP..!
 
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samemikejones said:
got a real tricky but fun problem, wheel A is going 35 rad/s, with I = 25 Kg*m2 and merges into wheel B with I = 15 Kg*m2, if they stick together at contact, find its angular velocity and change in Kinetic Energy...

PlEASE HELP:

So far, I have L = IW, or 8.8 x 10^2 kg m2/sec

and L = IW for oval to be at 9.8 x 10^2 kg m2/sec,

w = L/I
need some guidance from here...PLEASE HELP..!

Your first computation for the angular momentum looks fine. I have no idea where your second line comes from. The problem is not specific, but I assume they indend for you to assume wheel B starts at rest. The two wheels together have greater moment of inertial than either one separately. Angular momentum must be conserved. How do calculate the kinetic energy?
 
samemikejones said:
K.E. = 1/2 I omegah squared

OK, so you have an initial \omega for each wheel. Use conservation of angular momentum to find their final \omega and calculate the initial and final energies.
 

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