# A bullet goes through a ballistic pendulum, what is it's initial velocity?

• Nibbz
In summary, a 7.0-g bullet with a speed of 200 m/s is fired into a 1.5-kg ballistic pendulum. The block rises to a maximum height of 12 cm. To find the initial speed of the bullet, the Conservation of Momentum for Glancing Collisions with both X and Y components can be used. However, the angle at which the pendulum rises may need to be taken into account. Alternatively, the Conservation of Energy equation may also be used.
Nibbz

## Homework Statement

A 7.0-g bullet is fired into a 1.5-kg ballistic pendulum. The bullet emerges from the block with a speed of 200 m/s, and the block rises to a maximum height of 12 cm. Find the initial speed of the bullet.

## Homework Equations

Conservation of Momentum

## The Attempt at a Solution

I first converted all of my units into SI units. I then went to use the Conservation of Momentum for Glancing Collisions, with X and Y components, but I am confused as to what the components of the bullet are. All I know is that the pendulum rises at some angle to .12 m above it's original position and I'm not sure how to interpret this into an equation. Any assistance will be greatly appreciated.

Is it necessary to do this with Cons of momentum as Cons of energy seems easier?

## 1. What is a ballistic pendulum?

A ballistic pendulum is a device used to measure the velocity of a projectile by observing the motion of a pendulum after it has been struck by the projectile.

## 2. How does a ballistic pendulum work?

A ballistic pendulum works by taking advantage of the principle of conservation of momentum. When a projectile is fired into a pendulum, it transfers some of its momentum to the pendulum. By measuring the motion of the pendulum after the impact, the initial velocity of the projectile can be calculated.

## 3. Why is a ballistic pendulum used to measure velocity?

A ballistic pendulum is used to measure velocity because it is a simple and accurate method. It also allows for the measurement of high velocities that may be difficult to measure directly.

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

The accuracy of a ballistic pendulum can be affected by factors such as air resistance, friction in the pivot point of the pendulum, and the elasticity of the pendulum arm. These factors can cause the pendulum to lose some of its kinetic energy, leading to a lower calculated initial velocity for the projectile.

## 5. How can the initial velocity of a projectile be calculated using a ballistic pendulum?

The initial velocity of a projectile can be calculated by using the formula v = √(2gh), where v is the initial velocity of the projectile, g is the acceleration due to gravity, and h is the height of the pendulum's swing. This formula is derived from the conservation of momentum principle and can be used to calculate the initial velocity of the projectile after it has been fired into the pendulum.

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