A Mass on a Turntable: Conceptual

In summary, the conversation discusses the motion of a small metal cylinder on a rotating turntable, with a focus on the effects of changing the distance between the cylinder and the center of the turntable. The options for the motion of the cylinder at a new location are given, and the participants discuss the factors that could influence its speed and acceleration. It is determined that decreasing the radius of the cylinder will decrease its speed, but there is some confusion about whether the cylinder will rotate on its own axis. Overall, there is a need for further clarification and understanding of the problem.
  • #1
Vivee=)
15
0

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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  • #2
I don't see why the speed would increase... if [tex]\omega[/tex] the rate of rotation of the turntable is the same... then the speed of the cylinder is [tex]R\omega[/tex] 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...
 
  • #3
learningphysics said:
I don't see why the speed would increase... if [tex]\omega[/tex] the rate of rotation of the turntable is the same... then the speed of the cylinder is [tex]R\omega[/tex] 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.
 

Related to A Mass on a Turntable: Conceptual

What is a mass on a turntable?

A mass on a turntable refers to an object placed on a rotating platform, such as a record player or a lab turntable. This concept is often used in physics experiments to study rotational motion and centripetal force.

How does a mass on a turntable demonstrate centripetal force?

A mass on a turntable demonstrates centripetal force by showing how an object's velocity changes as it moves in a circular path. The centripetal force, which is directed towards the center of the circle, is responsible for keeping the object on its circular path.

What factors affect the motion of a mass on a turntable?

The motion of a mass on a turntable is affected by the mass of the object, the rotational speed of the turntable, and the distance between the object and the center of rotation. These factors determine the amount of centripetal force acting on the object and can affect its velocity and trajectory.

How can a mass on a turntable be used to calculate centripetal force?

By measuring the mass, speed, and distance of a mass on a turntable, the centripetal force acting on the object can be calculated using the formula F = mv^2/r, where F is the centripetal force, m is the mass, v is the speed, and r is the distance from the center of rotation.

What real-life applications can be demonstrated using a mass on a turntable?

A mass on a turntable can be used to explain and demonstrate various real-life phenomena, such as the rotation of planets and satellites, the motion of a car around a curved track, and the swinging of a pendulum. It also helps in understanding concepts like centrifugal force and centripetal acceleration in everyday objects.

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