PhysicsLAB Practice Problems
Torque, Pulleys, and Rotational Motion

Directions: On this worksheet you will practice using the basic formulas for torque and the subsequent rotational behavior.

Question 1  A pulley of radius R = 25 cm is created from a solid cylinder suspended on a frictionless axle. One end of a cord is wrapped around the pulley's edge while the other end is attached to a block having a mass of 280 grams. The system is initially at rest.

When the system is released, the mass falls 1.8 meters in 4.5 seconds. What was the linear acceleration of the mass?
Question 2  What is the tension in the cord while the mass is accelerating?
Question 3  What torque does the cord deliver to the pulley while the mass is decending?
Question 4  What angular impulse does the cord deliver to the pulley during the 4.5 seconds that the mass is decending?
Question 5  Based on the fact that the cord did not slip as the mass fell, what is the angular acceleration of the pulley?
Question 6  Based on these kinematics of the falling block, what is the pulley's experimental moment of inertia?
Question 7  How much potential energy did the block possess at the start of the experiment?
Question 8  What was the translational kinetic energy of the block at 4.5 seconds?
Question 9  What was the rotational kinetic energy of the pulley at 4.5 seconds?
Question 10  How much angular momentum does the pulley have at 4.5 seconds?
Question 11  Once the experiment was over, the pulley is placed on a scale and its mass is determinied to be 30 kg. Calculate its actual moment of inertia?
Question 12  What was the percent error for the experimental moment of inertia calculated in Question #3?
Question 13  Based on the data obtained and analyzed in this experiment, was mechanical energy conserved?
Question 14  If the pulley had been a wheel resembling a bicycle with the majority of its mass located in its rim and tire, but supported by thin, light-mass, wire spokes, which of the following would you expect to be true?

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