The question is,(adsbygoogle = window.adsbygoogle || []).push({});

You have a system of a weightless rod (length=1.00m)

with three masses suspended rigidly as indicated, with m1 and

m3 at the ends and m2 at 0.7m.

(m1=20kg, m2=30kg, m3=20kg)

The whole system is suspended from its centre-of-mass and is rotated with 25J of rotational kinetic energy. How many revolutions per second does it make in its rotational motion?

(The picture provided shows a rod attached to the ceiling by a rope. and the three masses are attached to the rod at the distances mentioned in the problem above (kinda like a seesaw))

I have a feeling that this question is worded wrongly..b/c I thought the only way that we can get a period T for this type of probelm is when the angular velocity is constant, but obviously in this problem there is angular acceleration (b/c there is a net torque). Therefore the angular velocity is actually changing constantly, so how can the rotational kinetic energy and the period be constant?

I hope I have explained it clearly. If not, please ask me for further clarification. Any help from you is much appreciated!

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# Homework Help: Rotational motion -angular energy+angular acceleration

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