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Bullet fired and penetrates a block of wood

  • Thread starter talaroue
  • Start date
  • #1
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1. Homework Statement [/b]

A rifle with a barrel length of 61.54 cm fires a 8.17 g bullet with a horizontal speed of 400 m/s. The bullet strikes a block of wood and penetrates to a depth of 8.9 cm.
What resistive force (assumed to be constant) does the wood exert on the bullet?


Homework Equations


Dynamics


The Attempt at a Solution



PHysics2.jpg
 
Last edited:

Answers and Replies

  • #2
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am i even in the right direction? If not where did I go wrong?
 
  • #3
Doc Al
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Did you give the correct attachment?
 
  • #4
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haha oops good catch give me a second
 
  • #5
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now its the correct image. Thank you for that.
 
  • #6
Doc Al
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Hint: Use energy considerations.
 
  • #7
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Is that the only way that we are able to solve this because we haven't gone over engeries in class yet?
 
  • #8
Doc Al
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Is that the only way that we are able to solve this because we haven't gone over engeries in class yet?
No, you can also use dynamics/kinematics. Start by finding the average acceleration.
 
  • #9
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Am i suppose to assume that the distance the bullet traveled is 70.44 cm? Which is the barrel length+ the depth of the bullet in the wood?
 
  • #10
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I got the anwser it was 7343.822 N.....only problem is I dont know how I got it I found someone who did this problem online and just plugged my numbers in his equation but it doesn't show how he derived the equation!
 
  • #11
LowlyPion
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  • #12
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I think working on physics so long actually made me worse at it. It was right in front of me I just needed you to remind me of Kinematics! just us xf=xi+(vf^2-vi^2)/2a....then multiply the mass of the bullet by acceleration and that gives me fs.....wow FML
 

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