Conservation of Energy Video Lab

Background

The conservation of energy is a main concept in science. To truly see this, we need to limit the system and the paths that the energy can follow. In the three videos, you will look to see if the conservation of energy holds and when it doesn’t, analysis the path of the energy.

Procedure

Before you can begin, you will need to get the videos from Direct Measurement - Energy for a Pendulum, a Roller Coaster and a Ballistics Pendulum. Download the file to your computer so that you can use Quicktime to collect the data. Directions for downloading are found on this page.

A Pendulum

Is energy conserved as a pendulum swings?

Data

• After the initial drop, what is the pendulum’s height?
• How many frames does it take the pendulum to cover the 10 cm at the bottom?
• How many frames does it take the pendulum to cover the 10 cm on the return at the bottom?
• What is the return height of the pendulum?
• The mass of the pendulum is 25.0 g.

Calculations

• What is the GPE after the release?
• What is the velocity of the pendulum at the bottom?
• What is the KE?
• What is the velocity of the pendulum on the return?
• What is the GPE on the return?

Questions

• Is the energy of the pendulum conserved? Support your response with data/calculations.
• Where does the energy go?

Roller Coaster 1

Was mechanical energy conserved?

Data

• What is the length of the coaster’s train?
• How many cars are in the train?
• How many passengers can ride the train?
• How many frames does it take the train to pass the lowest point?
• What is the frame rate of the video?
• The height of the tow hill is 63 m.
• The average mass of a car is 545 kg.
• The average mass of a rider is 50.0 kg.

Calculations

• What is the average mass of a fully loaded train?
• What is the GPE for a fully loaded train at the top?
• What is the KE for train at the lowest point?

Questions

• What kind of energy does the coaster have at the top of the ride?
• Was mechanical energy conserved? Support your response.
• Where is the missing energy?

Ballistic Pendulum

What was the velocity of the ball as it left the cannon?

Data

• What is the length of the pendulum?
• What is the angle of the pendulum at the maximum height?
• What is the distance and time of the ball as it leaves the cannon?

Calculations

• What is the maximum height of the pendulum?
• What is the velocity of the pendulum just after the ball hits the pendulum?
• What is the velocity of the ball as it left the cannon?

Questions

• Why is energy not conserved in this type of collision?
• What are the possible sources of error for this video?