A Mass on a Turntable: Conceptual

AI Thread Summary
When a small metal cylinder is moved from a distance R to R/2 on a rotating turntable, the speed of the cylinder increases due to the relationship between radius and tangential speed (v = Rω). The acceleration, which depends on the radius, also changes; specifically, the magnitude of the centripetal acceleration increases as the radius decreases. Participants in the discussion initially debated whether the speed would decrease or increase, with some confusion about the implications of the constant angular velocity of the turntable. Clarifications were made regarding the cylinder's motion and the effects of changing its position on the turntable. Ultimately, the consensus is that moving closer to the center increases both speed and acceleration.
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Homework Statement


A small metal cylinder rests on a circular turntable that is rotating at a constant rate. Let R be the distance between the cylinder and the center of the turntable. Now assume that the cylinder is moved to a new location R/2 from the center of the turntable. Which of the following statements accurately describe the motion of the cylinder at the new location?

A The speed of the cylinder has decreased.
B The speed of the cylinder has increased.
C The magnitude of the acceleration of the cylinder has decreased.
D The magnitude of the acceleration of the cylinder has increased.
E The speed and the acceleration of the cylinder have not changed.

There could be more than one answers.

Homework Equations



v^2/R=magnitude

The Attempt at a Solution



So I tried out this experiment. It moves at a constant motion around the center of the mass and the speed is constant. Since it says "R/2" I decresaed the radius and the speed increases. So I think B is one of the answers. What else should I be aware of?
 
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I don't see why the speed would increase... if \omega the rate of rotation of the turntable is the same... then the speed of the cylinder is R\omega where R is the radius... so a smaller radius implies smaller speed... unless I'm missing something...

I'm thinking the cylinder won't rotate about its own axis if it's placed initially at rest on the turntable... because the rotation of the turntable only imparts angular momentum about the vertical axis... the axis of the cylinder is perpendicular to the vertical axis...
 
learningphysics said:
I don't see why the speed would increase... if \omega the rate of rotation of the turntable is the same... then the speed of the cylinder is R\omega where R is the radius... so a smaller radius implies smaller speed... unless I'm missing something...

I'm thinking the cylinder won't rotate about its own axis if it's placed initially at rest on the turntable... because the rotation of the turntable only imparts angular momentum about the vertical axis... the axis of the cylinder is perpendicular to the vertical axis...

Oh, i see. I misinterpretted the problem. Thanks for the reply.
 

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