A pulley with a radius of 3.0 cm and a rotational inertia of 4.5 * 10^-³ kg . m² is suspended from the ceiling. A rope passes over it with a 2.0-kg block attached to one end and a 4.0-kg block attached to the other. The rope does not slip on the pulley. At any instant after the blocks start moving the object with the greatest kinetic energy is: A) the heavier block B) the lighter block C) the pulley D) either block (the two blocks have the same kinetic energy) E) none (all three objects have the same kinetic energy)

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Quizplus · Accepted Answer

The pulley has the greatest rotational kinetic energy, which is given by:$$K = \frac{1}{2}I\omega^2$$where I is the rotational inertia and ω is the angular velocity. The pulley has the greatest rotational inertia, so it will have the greatest kinetic energy.

A Pulley with a Radius of 3