# Ballistic Pendulum: Bullet Impact at 500m/s

• rsala
In summary, the problem involves a ballistic pendulum consisting of a block of wood hanging from a string and hit by a bullet traveling at 500m/s. The bullet has a mass of 0.006kg and passes through the block before it swings to a maximum angle of 12 degrees. The solution involves using the conservation of energy and momentum equations to calculate the final velocity of the bullet, which is found to be 327 m/s.
rsala

## Homework Statement

a ballistic pendulum is hit by a bullet traveling 500m/s , the ballistic pendulum is a block of wood hanging from a string.
the block of wood (1kg) is hanging from the string of 2.5m
the bullet has mass .006kg @ 500m/s
the bullet passes right through the block of wood before it makes any significant movement.
the block of wood swings to a max angle of 12 degrees with the vertical.

ive drawn out a microsoft paint image.
http://img512.imageshack.us/img512/262/bulletib5.jpg

## Homework Equations

conservation of energy
and momentum

## The Attempt at a Solution

here is my solution
please tell me if i got the correct answer, this is from a test i took yesterday

http://img246.imageshack.us/img246/5002/bullet2lv3.jpg

edit : I've made changes,, the correct initial velocity of the block .98 m/s
and the bullets initial momentum is 3 kg-m/s
and the final bullet velocity is 333.333,, is this correct?
thank you

Last edited by a moderator:
I assume the problem is to find the speed of the bullet after it passes through the block.

No, it's not correct.

(1) Recalculate a more accurate value for the change in height of the block.

(2) Recalculate the initial (post bullet) velocity of the block.

(3) Recalculate the initial momentum of the bullet. (It's not 6 kg-m/s.)

I see i made the mistake, the velocity of the block initially should be .98 m/s NOT 3.13

ic the wrong bullet momen. now, it is 3

so should the final velocity of the bullet be 333.3333 m/s?

or is it 327, ?
thank you

Last edited:
rsala said:
I see i made the mistake, the velocity of the block initially should be .98 m/s NOT 3.13
I get a slightly different value for the velocity.

ic the wrong bullet momen. now, it is 3
Right.

so should the final velocity of the bullet be 333.3333 m/s?
That's close to what I get.

or is it 327, ?
That's even better.

i wrote 333.333 on the test
now i don't know what to say, whether it got it wrong or not

## 1. How does a ballistic pendulum work?

A ballistic pendulum is a simple device used to measure the velocity of a projectile, such as a bullet. It consists of a pendulum with a known mass and length, and a catch mechanism to stop the pendulum's swing after it has been hit by the projectile. The height the pendulum swings to after impact is used to calculate the velocity of the projectile.

## 2. What is the purpose of testing bullet impact at 500m/s?

Testing bullet impact at 500m/s allows scientists to gather data on the effects of high-velocity impacts on various materials. This information can be used for research and development in fields such as ballistics, material science, and engineering.

## 3. How is the velocity of the bullet calculated using a ballistic pendulum?

The velocity of the bullet is calculated using the conservation of energy and momentum principles. The mass and length of the pendulum, as well as the height it swings to after impact, are used in a formula to determine the velocity of the bullet.

## 4. What factors can affect the accuracy of the measurement in a ballistic pendulum?

The accuracy of the measurement in a ballistic pendulum can be affected by various factors such as air resistance, friction in the pendulum's swing, and the precision of the catch mechanism. The weight and shape of the projectile can also impact the results.

## 5. What are the limitations of using a ballistic pendulum for measuring bullet impact?

One limitation of using a ballistic pendulum is that it can only measure the velocity of a single projectile at a time. Additionally, the accuracy of the measurement can be affected by external factors, as mentioned in the previous question. Furthermore, the ballistic pendulum may not be suitable for measuring the impact of high-velocity bullets, as the pendulum may not be able to swing to a measurable height after impact.

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