Plot motion of particle with constant speed and angular velocity

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Homework Help Overview

The problem involves a particle sliding inward with a constant speed on a rotating platform, requiring a plot of the particle's trajectory as it moves from a specified radius to zero. The context includes concepts of motion, angular velocity, and potentially inertial versus non-inertial reference frames.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants discuss the implications of constant speed and angular velocity on the trajectory, questioning whether the plot should consist of straight lines or if a different approach is needed in a rotating frame. There are inquiries about the nature of sliding and the effects of centripetal force on the particle's motion.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the problem. Some guidance has been offered regarding the reference frame and the implications of friction, but no consensus has been reached on the trajectory or the nature of the motion.

Contextual Notes

Participants note the absence of time in the problem statement and question how this affects the plotting of the trajectory. There is also a discussion about the implications of sliding without friction and the role of centripetal force in the motion described.

S_Flaherty
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Consider the problem of a particle sliding inwards with a constant speed c and starting at radius R=pc/Ω, on a platform rotating with a constant angular velocity Ω. Give a plot of the trajectory of the particle from r=R to r=0, for p=0.5, 1, 2, 6.


I'm a little confused on how to do this. If there is no acceleration, then would the plot just be a series of straight lines? And should I plot r vs t even though time isn't mentioned at all?
 
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"Sliding" would imply that there is no friction with the platform, in which case the trajectory should indeed be a straight line - in an inertial frame of reference. Are you perhaps supposed to find the trajectory in the platform's frame?
 
Also, how can something slide inward if it's moving in circular motion? Wouldn't centripetal force cause it to slide outward?
 
S_Flaherty said:
Also, how can something slide inward if it's moving in circular motion? Wouldn't centripetal force cause it to slide outward?

That's why I think there is no friction.
 

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