Bullet fired and penetrates a block of wood

In summary, the rifle fires a 8.17 g bullet and it penetrates to a depth of 8.9 cm. The wood exerts a resistive force on the bullet and it decelerates to a final velocity of 0.089 m.
  • #1
talaroue
303
0
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



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  • #2
am i even in the right direction? If not where did I go wrong?
 
  • #3
Did you give the correct attachment?
 
  • #4
haha oops good catch give me a second
 
  • #5
now its the correct image. Thank you for that.
 
  • #6
Hint: Use energy considerations.
 
  • #7
Is that the only way that we are able to solve this because we haven't gone over engeries in class yet?
 
  • #8
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.
 
  • #9
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
 

1. How does the speed of the bullet affect its ability to penetrate a block of wood?

The speed of the bullet directly affects its ability to penetrate a block of wood. The faster the bullet is traveling, the more kinetic energy it has, which allows it to overcome the resistance of the wood and penetrate deeper.

2. What factors determine the depth of penetration of a bullet into a block of wood?

The main factors that determine the depth of penetration of a bullet into a block of wood are the speed of the bullet, the density of the wood, and the shape and composition of the bullet. Other factors such as the angle of impact and the moisture content of the wood can also play a role.

3. Can a bullet be stopped by a block of wood?

Yes, a bullet can be stopped by a block of wood. The ability of the wood to stop the bullet depends on its density and thickness, as well as the speed and type of bullet being fired. In some cases, the bullet may not fully penetrate the wood and may become lodged in the block.

4. How does the type of wood affect the penetration of a bullet?

The type of wood can have a significant impact on the penetration of a bullet. Harder, denser woods such as oak or maple will be more difficult for a bullet to penetrate compared to softer woods like pine or plywood. The grain and direction of the wood fibers can also influence the bullet's path.

5. Can a bullet change direction or trajectory when penetrating a block of wood?

Yes, a bullet can change direction or trajectory when penetrating a block of wood. This can occur due to the irregularities in the wood's density and grain, as well as the shape and composition of the bullet itself. The angle of impact and any obstacles within the wood can also cause the bullet to change direction.

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