Physics 182A/195L Lab 8: Ballistic Pendulum

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Questions and Answers

What energy type does the pendulum possess at the highest point of its swing?

Thermal energy

Potential energy (correct)

Mechanical energy

Kinetic energy

Which principle is used to analyze the motion of the pendulum after the collision with the ball?

Newton's second law

Conservation of energy (correct)

Newton's third law

Conservation of momentum

What is the primary challenge when measuring the height that the pendulum reaches?

The pendulum's height is too low

The pendulum swings too quickly

The pendulum moves in the x-direction (correct)

The pendulum's mass is too heavy

How is the speed of the ball after the collision related to the maximum height the pendulum swings to?

It is directly proportional to height Signup and view all the answers

What is the first step of the experimental procedure for the ballistic pendulum?

Attach the projectile launcher to the ballistic pendulum Signup and view all the answers

What is the significance of combining the equations from conservation of momentum and conservation of energy?

To find a relationship between angles and speeds Signup and view all the answers

What does the potential energy of the pendulum depend on at its maximum height?

The mass of the pendulum Signup and view all the answers

What happens to the pendulum's kinetic energy just before it reaches its maximum height?

It converts entirely into potential energy Signup and view all the answers

What should the launch angle of the projectile launcher be set to before use?

Zero degrees Signup and view all the answers

What is the first step for loading the projectile into the launcher?

Swing the pendulum out of the way Signup and view all the answers

What should you do if the angle indicator is not at zero degrees when the pendulum is in its hanging position?

Account for this difference in your calculations Signup and view all the answers

How should the pendulum be balanced on the meter stick?

By locating the center of mass over the pivot point Signup and view all the answers

What should you record after launching the ball and allowing the pendulum to swing?

The maximum angle reached during the swing Signup and view all the answers

If the angle indicator does not start at zero, what must be done with the recorded angles?

Subtract the starting value from the final value Signup and view all the answers

What mass should be measured if you are calculating the mass of the ball?

The mass of just the ball Signup and view all the answers

What is the purpose of resetting the angle indicator after each launch?

To ensure accurate angle measurements each trial Signup and view all the answers

What is the first step needed to prepare for the Freeflight Experiment?

Attach Photogates to the launcher using the Photogate Bracket. Signup and view all the answers

What should be verified before proceeding with the launch of the ball?

No one should be in the way of the ball. Signup and view all the answers

How many times should the speed measurement be repeated?

Five times Signup and view all the answers

To determine the average speed, which values need to be calculated from Table 3?

The total of all measurements divided by five. Signup and view all the answers

What is the purpose of using Photogate 1 and Photogate 2 in the experiment?

To measure the launch speed of the ball accurately. Signup and view all the answers

What is one way to calculate the percentage of kinetic energy lost during the collision?

Using the formula: K.E. lost = (K.E. before - K.E. after) / K.E. before. Signup and view all the answers

Which factor is NOT part of the variables recorded in Table 2?

Launch angle of the ball Signup and view all the answers

Which aspect of the experiment could affect the accuracy of the launch speed measurements?

Air resistance acting on the ball during flight. Signup and view all the answers

What is the primary purpose of a ballistic pendulum?

To measure the speed of a projectile Signup and view all the answers

Which physical principle is primarily used to analyze the collision in a ballistic pendulum experiment?

Conservation of momentum Signup and view all the answers

After the collision, how does the pendulum's height relate to the initial speed of the projectile?

Higher initial speed results in higher height Signup and view all the answers

What type of collision occurs between the projectile and the pendulum in a ballistic pendulum setup?

Perfectly inelastic collision Signup and view all the answers

In a ballistic pendulum experiment, what happens to the pendulum mass after the collision?

It swings upward converting kinetic energy to potential energy Signup and view all the answers

What must be known to determine the initial speed of the ball using the ballistic pendulum?

The height reached by the pendulum after the impact Signup and view all the answers

What does conservation of momentum imply about the speeds of the projectile and the pendulum after the collision?

They move together at a common speed post-collision Signup and view all the answers

Which variable does NOT influence the outcome of the ballistic pendulum experiment?

The height from which the pendulum is dropped Signup and view all the answers

Study Notes

Ballistic Pendulum Overview

A ballistic pendulum is utilized to measure projectile speed through its impact and subsequent swing.
The system consists of a projectile (metal ball) that collides with a pendulum mass, capturing the projectile.

Collision Dynamics

The collision is defined as perfectly inelastic since the projectile becomes embedded in the pendulum.
Conservation of momentum principle allows calculation of the initial speed of the projectile and its speed after the collision.
The relationship can be expressed as a function of the masses of the projectile and pendulum and their velocities.

Energy Transfer

Immediately after the collision, kinetic energy of the combined system converts to potential energy as the pendulum swings upward.
At maximum swing height, the pendulum has potential energy and is momentarily at rest.
The conservation of energy principle reveals a formula connecting the initial speed of the projectile to the height reached by the pendulum.

Mathematical Relations

A derived formula equates the initial speed of the ball to the maximum height the pendulum swings after impact.
Further adjustments can express this relationship in terms of the angle of swing, facilitating easier measurement using standard protractor tools.

Experimental Setup

Part A: Ballistic Pendulum Experiment

Ensure proper alignment by using a thread and bead to level the projectile launcher with the pendulum.
Record the maximum swing angle reached by the pendulum during multiple launches.
Calculate the pendulum arm length and determine the change in height (Δh) for accurate measurements.

Part B: Freeflight Experiment

Attach photogates to measure ball speed prior to collision.
Record launch speed in multiple trials to evaluate consistency and averages.

Data Collection

Use various tables to log angles, pendulum characteristics, and launch velocities from experiments.
Average angles and velocities are essential for final analyses.

Analysis Questions

Calculate percent difference between calculated and measured launch velocities to assess accuracy.
Determine which method (pendulum capture or photogate measurement) yields a more reliable launch speed.
Assess kinetic energy lost during the collision as a percentage of total energy for system efficiency evaluation.

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Description

This lab report focuses on the ballistic pendulum, a system designed to measure projectile speed. Students will explore the theoretical underpinnings and practical applications of this apparatus in their experimental work. Collaborate with lab partners to analyze data and report findings.