A puck on a frictionless air hockey table has a mass of 5.0 kg and is attached to a cord passing through a hole in the surface as in the figure. The puck is revolving at a distance 2.0 m from the hole with an angular velocity of 3.0 rad/s. The angular momentum of the puck (in kg⋅m²/s) is A)80 B)20 C)30 D)60 E)50

Question

Quizplus · Accepted Answer

The angular momentum of an object is given by the formula L = Iω, where I is the moment of inertia and ω is the angular velocity. 
Since the puck is attached to a cord and revolving around a fixed point, its moment of inertia can be calculated as I = mr^2, where m is the mass of the puck and r is the distance from the puck to the fixed point (in this case, the hole). 
Plugging in the given values, we get: 
I = (5.0 kg)(2.0 m)^2 = 20 kg⋅m^2 
Then, using the formula for angular momentum: 
L = Iω = (20 kg⋅m^2)(3.0 rad/s) = 60 kg⋅m^2/s 
Therefore, the answer is D) 60.

A Puck on a Frictionless Air Hockey Table Has a Mass