A 0.25 kg air-hockey puck slides on a nearly frictionless horizontal table
PHYSICS · Multi-part · AP · Physics 1: Algebra-based · Energy and Momentum of Rotating Systems · Energy and Momentum of Rotating Systems
Problem
A 0.25 kg air-hockey puck slides on a nearly frictionless horizontal table. Its position as a function of time is described by
r(t)=(0.30t)^+0.40^m,
where t is in seconds. The puck’s speed remains constant for the time interval considered.
Treat the puck as a point particle and take the origin of coordinates as the reference point.
(a) Derive an expression for the puck’s angular momentum about the origin as a function of time.
(b) Evaluate the magnitude and sign (into or out of the page) of the angular momentum at t = 2.0 s.
(c) Suppose a constant torque, directed opposite to the angular momentum found in part (b), is applied beginning at t = 2.0 s and lasting until t = 2.5 s. Determine the magnitude of this torque required to bring the puck’s angular momentum to zero at t = 2.5 s.