- #1
Pochen Liu
- 52
- 2
Homework Statement
How come I can't get the correct answer using Energy as a way to solve this?
Homework Equations
3. The Attempt at a Solution [/B]
The answers use conservation of momentum which makes perfect sense and I understand that, however I used an energy approach where E(flywheel) = E(HST)
So E(flywheel) = 0.5 * 43.2 * 3.22^2 = 223.967J
E(HST) = 0.5 * I * 0.07539^2 (I know this is the correct angular velocity from the answers)
When I solve this I = 78807.427 Kgm^2, the answer is 1850.
What am I doing wrong conceptually? And what have I done, as in, if given a different situation where would have my working have resulted in the correct answer?