Bullet fired at a block of wood

In summary, the problem involves a bullet being shot into a block, causing it to lift upward and penetrate the block in a time interval of 0.001 s. The impulse on the block due to the capture of the bullet can be found using conservation of momentum and is equal to the change in momentum of the block. The time given is not relevant for this question.
  • #1
Motorboar
6
1

Homework Statement



An 19-g bullet is shot vertically into an 5-kg block. The block lifts upward 5 mm. The bullet penetrates the block in a time interval of 0.001 s. Assume the force on the bullet is constant during penetration. The impulse on the block due to capture of the bullet is closest to:

Homework Equations


Impulse = P_2 - P_1


The Attempt at a Solution


1/2(mbullet + mblock)v2^2 = (mbullet + mblock)gy
v2 = sqrt(2gy)
v1 = ((mbullet + mblock)/mbullet)*v2
Impulse = m2v2 - m1v1

Comes out wrong, and didn't use the time given. I modeled my solution after a ballistic pendulum problem. Any pointers?
 
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  • #2
try to do it using conservation of momentum, instead of conservation of energy. total mechanical energy is not conserved here, as the block got permanent deformations by the bullet.
 
  • #3
Motorboar said:

The Attempt at a Solution


1/2(mbullet + mblock)v2^2 = (mbullet + mblock)gy
v2 = sqrt(2gy)
This is good. Note that you are asked to find the impulse on the block, so what is the change in momentum of the block?

The time is irrelevant for this question. (But I suspect there are other parts to this problem.)
 

1. How does a bullet affect a block of wood upon impact?

When a bullet is fired at a block of wood, it creates a high amount of force and energy upon impact. This force causes the wood to compress and deform, and the energy is transferred to the wood in the form of heat and sound.

2. Can a bullet penetrate through a block of wood?

It depends on the type of bullet and the density of the wood. A high velocity and high caliber bullet is more likely to penetrate through a block of wood than a lower velocity and lower caliber bullet. However, thicker and denser wood may be able to resist penetration from a bullet.

3. What factors affect the damage caused by a bullet to a block of wood?

The velocity, caliber, and type of bullet all play a role in the damage caused to a block of wood upon impact. Additionally, the density and thickness of the wood, as well as the angle of impact, can also affect the damage caused.

4. How does the shape of the bullet affect its impact on a block of wood?

The shape of the bullet can greatly influence its impact on a block of wood. A pointed or sharp bullet is more likely to penetrate through the wood, while a round or blunt bullet may create a larger surface area of impact and cause more damage to the wood upon impact.

5. Is there a difference in the impact of a bullet on different types of wood?

Yes, different types of wood have varying densities and strengths, which can affect the impact of a bullet. For example, a bullet may penetrate through a softer wood like pine more easily than a harder wood like oak. Additionally, the grain and direction of the wood can also impact the damage caused by a bullet upon impact.

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