Calculating the Distance of a Block from a Table After a Bullet Collision

In summary, the conversation discusses the calculation of the final velocity of a bullet embedded into a block of wood, and the time it takes for the block to hit the floor when dropped from a table. The final velocity is determined to be 0.9504 m/s, and the calculated time in air is corrected to be 0.1325 seconds. The correct formula is used to find the distance the block travels before hitting the floor.
  • #1
mikefitz
155
0
A 0.01-kg bullet traveling horizontally at 400.1 m/s strikes a 4.2-kg block of wood sitting at the edge of a table. The bullet is lodged into the wood. If the table height is 1.3 m, how far from the table does the block hit the floor?

I have calculated the final velocity of the bullet and block to be:

.01(400.1)=.01(Vf)+4.2(Vf)

Vf= .9504 m/s

So, now I have the velocity of the bullet embedded into the block. The time in the air is 1.3/9.82 = .1325 seconds.

.1325s * .9504 m/s = .1259 meters

Why is this wrong? Thanks
 
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  • #2
mikefitz said:
So, now I have the velocity of the bullet embedded into the block. The time in the air is 1.3/9.82 = .1325 seconds.
How did you determine this? How long does it take for something to fall 1.3 meters?
 
  • #3
mikefitz said:
Why is this wrong? Thanks
Your calculated time in air is wrong.
 
  • #4
OlderDan said:
Your calculated time in air is wrong.

Sorry, I meant to type 1.3/9.81 = .1325 -- the 9.82 was a typo.
 
  • #5
mikefitz said:
Sorry, I meant to type 1.3/9.81 = .1325 -- the 9.82 was a typo.
That is not the problem. You are not calculating time. It would help you to keep your units in your calculations. Distance divided by acceleration is not time.
 
  • #6
Stupid me, I used this formula and found the correct answer: http://www.glenbrook.k12.il.us/gbssci/Phys/Class/1DKin/U1L6b4.gif

thanks!
 
Last edited by a moderator:

1. How does a bullet's mass affect its collision with a block?

The mass of a bullet affects its collision with a block in two ways. First, a heavier bullet will have more kinetic energy, meaning it will cause more damage upon impact. Second, a heavier bullet will have more momentum, meaning it will be more difficult to stop or deflect upon collision.

2. What role does the velocity of a bullet play in a bullet and block collision?

The velocity of a bullet is a major factor in a bullet and block collision. A higher velocity means the bullet has more kinetic energy and momentum, resulting in a more forceful impact and potentially more damage to the block.

3. Can a bullet completely penetrate through a block?

It is possible for a bullet to completely penetrate through a block, depending on factors such as the bullet's velocity, mass, and the material and thickness of the block. However, other factors such as the angle of impact and the shape of the bullet can also play a role.

4. How does the angle of impact affect a bullet and block collision?

The angle of impact can greatly affect a bullet and block collision. If the bullet hits the block at a perpendicular angle, it will transfer more energy and momentum to the block, potentially causing more damage. However, if the bullet hits at an oblique angle, some of the energy and momentum will be deflected, resulting in less damage to the block.

5. What factors can influence a bullet's trajectory in a bullet and block collision?

There are several factors that can influence a bullet's trajectory in a bullet and block collision. These include the velocity and mass of the bullet, the angle of impact, the shape and material of the bullet, and any external forces such as wind or gravity. Additionally, the material and thickness of the block can also affect the bullet's trajectory upon impact.

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