A student whirls a small rubber stopper of mass in a horizontal circle at the end of…
PHYSICS · Multi-part · AP · Physics 1: Algebra-based · Torque and Rotational Dynamics · Torque and Rotational Dynamics
Problem
A student whirls a small rubber stopper of mass 200g in a horizontal circle at the end of a light string that is 0.40m long. The stopper completes each revolution in 0.20s.
Answer the following questions, showing all work and including proper units.
(a) Convert all given quantities to SI base units and calculate the stopper’s moment of inertia about the central axis of rotation.
(b) Determine the rotational kinetic energy of the stopper at the given speed.
(c) Without changing the tangential speed of the stopper, the student shortens the string so that its length becomes 0.20m. Calculate the new moment of inertia and compare it quantitatively with the value found in part (a).