Rotating flywheel problem

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Bolter
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Homework Statement
Working out torque from rotating flywheel
Relevant Equations
Rotational equivalent of SUVAT equations
Torque = moment of inertia * angular acceleration
Hey everyone!

Was trying to answer this question and was wondering if this was the right way to go about it?

Printed physics problem part (b): A flywheel with a moment of inertia of 3.50 kg m² is rotating at 45 rpm. Determine the torque required to bring it to rest in 5.0 revolutions.

Handwritten derivation of torque from rotational kinematics: tau = I alpha, alpha = tau/I, omega^2 = omega0^2 + 2 alpha theta, with omega = 0, omega0 = 3pi/2 rad/s and theta = 10pi, leading to tau = -1.24 Nm, stated as 1.24 Nm to 2 dp.


Any help would be really appreciated!
 
Sounds good.

Just remember to include units (I know it's a pain but as a "pseudo-physicist" I had to point it out.). Usually, including units throughout the entire problem is a good way to check if the solution is correct. If the units cancel out as desired, then your solution should be correct (unless you made some silly arithmetic mistake).
 
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KDPhysics said:
Sounds good.

Just remember to include units (I know it's a pain but as a "pseudo-physicist" I had to point it out.). Usually, including units throughout the entire problem is a good way to check if the solution is correct. If the units cancel out as desired, then your solution should be correct (unless you made some silly arithmetic mistake).

Ok thanks, I'll try to do that more often until it becomes second nature. It's not that I don't want to add units but always forget to :rolleyes:
 
Yeah... I feel you. You'll get used to it after a while.