Rigid Body Dynamics: balls colliding

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Homework Help Overview

The discussion revolves around analyzing the dynamics of two colliding balls on a billiard table, focusing on both 1D and 2D collisions. The original poster seeks to understand the energy transfer during these collisions, particularly regarding the translational and rotational energy of the rolling ball.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • The original poster questions whether the rolling ball transfers all its translational energy while retaining its rotational energy after the collision. They also inquire about alternative methods to analyze the collisions.

Discussion Status

Participants have engaged in discussing the implications of momentum conservation and the effects of spin on the cue ball's trajectory after a collision. There is an acknowledgment of the complexity involved in the calculations, with some expressing difficulty in approaching the problem.

Contextual Notes

Participants note the specific conditions of the collisions, including the masses of the balls, their radii, and the frictional forces involved. The discussion reflects on the practical aspects of billiards gameplay, such as the retention of rotational momentum.

AndersLau
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Homework Statement


I want to analyse two colliding balls, rolling flat on a billiard table.
I have recorded two collisions from above the table. A 1D collision and a 2D collision.
In both collisions only 1 of the balls are rolling before the collision.

Known is:
mass of the balls: m1=207g, m2=203g
their radius: r=3cm
friction between table and balls: F1=0.47N, F2=0.46N
The velocity of the balls right before and after the collision.
I'm supposed to be using some physics on rigid body dynamics. From the video you can see, that even though the collision is in 1D, the rolling ball keeps rolling after it has hit the other. My 1 question is, does the rolling ball transfer all of its translational energy, and keeps all the rotational itself? Or how does it work?

In which other ways could i analyze these situations?

Thank you.
 

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AndersLau said:

Homework Statement


I want to analyse two colliding balls, rolling flat on a billiard table.
I have recorded two collisions from above the table. A 1D collision and a 2D collision.
In both collisions only 1 of the balls are rolling before the collision.

Known is:
mass of the balls: m1=207g, m2=203g
their radius: r=3cm
friction between table and balls: F1=0.47N, F2=0.46N
The velocity of the balls right before and after the collision.



I'm supposed to be using some physics on rigid body dynamics. From the video you can see, that even though the collision is in 1D, the rolling ball keeps rolling after it has hit the other. My 1 question is, does the rolling ball transfer all of its translational energy, and keeps all the rotational itself? Or how does it work?

In which other ways could i analyze these situations?

Thank you.

In a normal billiards game the cue ball certainly retains its rotational momentum after collision. In that way the [very] skillful player is able to cause the cue ball to move to just about any position they wish, after striking the other ball.

Even less skilled amateurs can use back spin, top spin and side spin to make the cue ball jag off in a desired direction - including coming back towards the player.
Indeed it takes a fair amount of skill to ensure the cue ball has no spin at all when it strikes the target ball.
 
okay, thank you.
Do you have any relevant calculations in mind? I find it a little tough.
 
AndersLau said:
okay, thank you.
Do you have any relevant calculations in mind? I find it a little tough.

Not really - though conservation of momentum says that without a head on collision, the cue ball can't stop completely.
 

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