Conservation of Momentum and Energy

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The discussion focuses on the conservation of linear and angular momentum in a physics problem involving a block and clay. The key equations for momentum conservation are presented, indicating that the total momentum before and after the impact should be equal. The participant expresses uncertainty about whether their understanding of momentum conservation is correct, particularly regarding the potential energy change as the system moves. However, it is clarified that potential energy considerations are separate from momentum conservation. The conversation emphasizes the importance of distinguishing between momentum and energy in analyzing the system's dynamics.
ryankunzzz
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Homework Statement


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Homework Equations


Conservation of liner and angular momentum
H1=H2
r x M1V1= r x M2V2

G1=G2
M1V1=M2V2

The Attempt at a Solution


I've gotten an equation for the velocity of the block and clay after the impact, and I also know that when the block reaches the highest point of its arc, its linear velocity is going to be the same as the velocity of the cart. Is the momentum going to be conserved and I can say MbV1=Vtot(M1+M2+M3)
 
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ryankunzzz said:
Is the momentum going to be conserved and I can say MbV1=Vtot(M1+M2+M3)
It seems like that would be true. On the other hand, I'm thinking, "It seems too easy. Am I missing something?" But I can't think of what that might be.
 
ryankunzzz said:
Is the momentum going to be conserved and I can say MbV1=Vtot(M1+M2+M3)
Yes, and I believe that is where the hint is directed.
 
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But what about the about the change in potential energy as the arm swings upward?
 
ryankunzzz said:
But what about the about the change in potential energy as the arm swings upward?
What about it? That's energy, not momentum.
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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