Bullet fired and penetrates a block of wood

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Homework Help Overview

The problem involves a bullet fired from a rifle that penetrates a block of wood, with the goal of determining the resistive force exerted by the wood on the bullet. The context includes dynamics and kinematics as the primary subject areas.

Discussion Character

  • Mixed

Approaches and Questions Raised

  • Participants explore various methods to solve the problem, including energy considerations and dynamics/kinematics. Questions arise regarding the appropriateness of the methods given the class curriculum and the assumptions about distances involved.

Discussion Status

The discussion is active, with participants sharing attempts and questioning their approaches. Some guidance has been offered regarding the use of kinematics and dynamics, and there is acknowledgment of the need to clarify assumptions about distances. Multiple interpretations of the problem are being explored.

Contextual Notes

Participants note that they have not covered energy concepts in class, leading to uncertainty about the methods available for solving the problem. There is also a mention of confusion regarding the distance the bullet travels.

talaroue
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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
 
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am i even in the right direction? If not where did I go wrong?
 
Did you give the correct attachment?
 
haha oops good catch give me a second
 
now its the correct image. Thank you for that.
 
Hint: Use energy considerations.
 
Is that the only way that we are able to solve this because we haven't gone over engeries in class yet?
 
talaroue said:
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.
 
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
I got the anwser it was 7343.822 N...only problem is I don't 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!
 
  • #12
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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