- #1

ac7597

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- Homework Statement
- Vasily Kosmonaut takes a spacewalk near an alien artifact which is floating in space, somewhere between Mars and Jupiter. The object appears to be a large hoop of some shiny substance, with radius R=6 meters and mass M=524 kg. The object is spinning slowly at an angular velocity of ω=0.16 radians per second.

What is the object's moment of inertia?

What is the object's rotational kinetic energy?

Vasily approaches the object and sticks out his hand to touch it. He presses his glove against the outer rim of the spinning hoop with a normal force of F=57 N. The coefficient of kinetic friction between his glove and the shiny surface is μk=0.25.

What is the magnitude of the torque applied to the object by Vasily?

The object begins to rotate more slowly. What is the magnitude of the angular acceleration of the hoop?

If Vasily maintains this force on the surface, how long will it take for the artifact to stop spinning?

- Relevant Equations
- I= mass * radius^2

KE=(1/2) (I) (angular velocity)^2

torque= F* (distance)

I= 524kg * 6m^2 = 18.86E3kg*m^2

KE=(1/2) (18.86E3kg*m^2) (0.16 rad/s )^2= 241.5 J

torque= 0.25* 57N* (6m)=85.5 N*m

KE=(1/2) (18.86E3kg*m^2) (0.16 rad/s )^2= 241.5 J

torque= 0.25* 57N* (6m)=85.5 N*m