Understanding the Motion of a Falling Rod on a Frictionless Surface

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Discussion Overview

The discussion revolves around the motion of a rod that is falling on a frictionless surface after being given a slight push. Participants explore the nature of the rod's movement, specifically whether it will rotate purely or also translate forward as it falls.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant suggests that the center of mass (CM) of the rod moves in circular motion, leading to an outward pull that causes forward movement.
  • Another participant questions the visualization of the motion and asks for clarification to better understand the dynamics involved.
  • A participant provides a visual aid to help illustrate the motion of the rod and seeks to clarify whether the rod will rotate purely or have translational velocity in addition to rotation.
  • It is proposed that on a frictionless surface, the lower end of the rod will slip to the right while the CM moves vertically downward, indicating a combination of translational motion and rotation around the CM.
  • One participant raises a question about the necessity of a net force acting on the lower end of the rod for it to slip on the surface.
  • A later reply indicates that one participant has understood the explanation provided.

Areas of Agreement / Disagreement

Participants express differing views on whether the rod will purely rotate or also translate. The discussion remains unresolved as multiple competing perspectives are presented without consensus.

Contextual Notes

There are assumptions regarding the nature of forces acting on the rod and the conditions of motion that are not fully explored, such as the implications of the frictionless surface on the rod's movement.

nil1996
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A rod initially held vertically is falling on a frictionless surface when given a slight push.I just want to how the rod would move.I am thinking that the rod as a whole will move forward and also rotate about the point on the ground.

Why the rod is moving forward?(if you ask me)
I think that the CM is going in circular motion and thus will experience an outward pull. This force will take the rod forward.

But i have heard that the rod purely rotates and does not move forward as a whole.
check this link http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=2541
What is wrong in my argument?
 
Last edited:
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I'm having trouble visualizing what you are saying. Could you be a little more explicit? Then I, as well as others, would be able to help you.
 
Legaldose said:
I'm having trouble visualizing what you are saying. Could you be a little more explicit? Then I, as well as others, would be able to help you.

here is a picture
http://img191.imageshack.us/img191/3926/lyj9.png

I want to know if the rod will rotate purely or have a translational velocity with rotation?
 
Last edited by a moderator:
nil1996 said:
I want to know if the rod will rotate purely or have a translational velocity with rotation?

If the surface is frictionless ,as in the picture,the lower end slips on the surface towards right ,in a manner such that the CM of the rod moves vertically downwards .You can consider the motion of the rod as a combination of translation of CM + Rotation around the CM.

I have made a rough sketch .The red dot shows the CM.
 

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Tanya Sharma said:
If the surface is frictionless ,as in the picture,the lower end slips on the surface towards right ,in a manner such that the CM of the rod moves vertically downwards .You can consider the motion of the rod as a combination of translation of CM + Rotation around the CM.

I have made a rough sketch .The red dot shows the CM.

For the end to slip should there be any net force acting on it?
 
I got it
thanks a lot:smile:
 

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