Solving Rotational Problem: Conserving Momentum, Energy & Mass

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In the discussion on solving a rotational problem involving a stick and a ball, key points include the conservation of linear momentum, angular momentum, and kinetic energy during an elastic collision. The participant is uncertain about how to apply these conservation laws simultaneously to determine the mass of the ball that allows it to remain at rest post-collision. Clarification is provided that "elastic" refers to a collision with no loss of kinetic energy, indicating a coefficient of restitution of 1. The complexities of balancing these conservation principles are highlighted, emphasizing the need for a comprehensive approach to the problem. Understanding these concepts is crucial for solving the collision scenario effectively.
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Homework Statement


A stick of length L and mass M lies on a frictionless horizontal surface on which it is free to move in anyway.
A ball of mass m moving with speed v collides elastically with the stick at a distance d below its centre.
(a) Which quantities are conserved in this collision?
(b) What must be the mass of the ball so that it remains at rest immediately after collision?



Homework Equations





The Attempt at a Solution


Here if we conserve linear momentum,
we get mv=Mv1 (As the ball remains at rest.)
But I don't think this is right because if we conserve angular momentum, then we get something else, and if we conserve kinetic energy, then we get something else.
So fow do i go about this question?
 
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Hi iitjee10! :smile:

i] in any collision (with no external forces), both momentum and angular momentum are always conserved

ii] what does "elastically" mean?
 
ii] what does "elastically" mean?
It means they collide with no loss of kinetic energy. :wink:
 
elastically means coefficient of restitution is 1
 

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