Calculating Bullet Penetration: Momentum vs Coefficient of Friction

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Discussion Overview

The discussion revolves around calculating the penetration depth of a bullet into a block, focusing on the role of momentum conservation and the coefficient of friction. Participants explore the necessary information and variables required to solve the problem, including the context of the block's motion and resistance forces.

Discussion Character

  • Exploratory, Debate/contested, Conceptual clarification

Main Points Raised

  • One participant asserts that the problem cannot be solved without the coefficient of friction, questioning the sufficiency of the information provided.
  • Another participant suggests that the full problem statement may not have been given, indicating a need for clarification.
  • Several participants highlight the importance of additional variables, such as whether the block is part of a pendulum or if it slides on a surface, which would affect the calculations.
  • A resistance force is mentioned as necessary for solving the problem, indicating that internal dynamics within the block must be considered.
  • Some participants speculate about the possibility of miscommunication regarding the original question, suggesting that the issue may stem from a misunderstanding of the problem's requirements.

Areas of Agreement / Disagreement

Participants generally agree that the problem lacks sufficient information and that multiple variables need to be clarified. There is no consensus on how to approach the problem due to the missing details.

Contextual Notes

Limitations include the absence of specific details regarding the block's motion, the nature of the resistance forces, and the overall context of the problem, which are crucial for a complete analysis.

CrazyNeutrino
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I shoot a bullet of mass m with velocity v against a block of mass M.
Find how far the bullet penetrates the block. This problem turned up in my friends examination and I believe it can't be done without the coefficient of friction. Am I right or can this be calculated using conservation of momentum. If so please show me how.
 
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You're right: Not enough information is given. (Is that the full problem statement?)
 
I think there are some variables missing:
Do you want the depth of the impact, or the length the block travels afterwards?
Is the big block part of a pendulum? (very common problem, needs length of pendulum)
Does the big block slide on a surface? (quite common problem, needs coefficient of friction)
 
Last edited:
A resistance force is needed to solve the problem inside the block.
 
No, I guess he didn't give me the entire question
 
I'm guessing he couldn't do it because he didn't read it properly.
 
Maybe. I need to ask him for his question paper
 

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