# Fly Wheel Mass

1. Oct 21, 2009

### Kev1n

1. I do not even know where to start here, any help is much appreciated

A flywheel (a) with a mass of 100 kg and radius of gyration 1200mm rotates at 150 revs min^-1 (clockwise). The kinetic energy of this flywheel is to be reduced by 20% by impacting it with a second flywheel (b) rotating at 80 revs min^-1 in the opposite direction,such that they have the same (clockwise) angular velocity after impact.

A) Calculate the required mass of the flywheel (b) if its radius of gyration is 800mm

B) Calculate the energy lost to the surroundings.

C) Is the impact elastic? why

2. I=MK^2

3. Totally stumped

2. Oct 25, 2009

### Kev1n

A pointer in the right direction would help

3. Oct 25, 2009

### Redbelly98

Staff Emeritus
Since you can calculate I, as well as ω, what other quantities or properties depend on I and ω? Are any of those quantities conserved during the "collision"?

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