PH 115 Online Lab 8: Conservation of Energy

PH 115 Online Lab 8: Conservation of EnergyOBJECTIVES
1. To practice calculating kinetic and potential energy
2. To test the conservation of energy is three scenarios.

MEASURING ENERGY
• In this lab, we will measure the energy in three events: a ball falling, a toy popper popping, and a pendulum swinging. For each event, we will determine the kinetic, potential, and total energy of the object in an effort to test the conservation of energy.
• Download the video of each event (in Firefox or Chrome, you can select “Save Page As” from the file menu):
o Ball Drop: (http://dl.dropbox.com/u/64459320/balldrop.mp4)
o Popper: (http://dl.dropbox.com/u/64459320/popper.mp4)
o Pendulum: (http://dl.dropbox.com/u/64459320/pendulum.mp4)
• We will use video analysis in Logger Pro to measure the energy of the object in each video.
• For your reference, you should use the following equations within Logger Pro for your calculated columns:
o Potential Energy = mass • 9.8 • Y
o Kinetic Energy = ½ • mass • (X velocity ^2 + Y Velocity ^2)
o Total Energy = Potential Energy + Kinetic Energy
o The ball and the popper both have a mass of 0.050 kg.

A FALLING BALL
• Use Logger Pro to analyze the motion of the ball drop.
• Create a graph of the potential, kinetic, and total energy of the ball as it falls.
• Take a screenshot of your graph and insert it below.
• Answer the following questions using your graph:
o Over which portion of the event does energy appear to be conserved?

o How would you explain portions of the graph where the total energy is not constant? (Note that “human error” is not a sufficient explanation. If you made a mistake, go back and collect your data over again.)
A POPPING TOY
• Use Logger Pro to analyze the motion of the popping toy.
• Create a graph of the potential, kinetic, and total energy of the toy as it goes up and back down.
• Take a screenshot of your graph and insert it below.
• Answer the following questions using your graph:
o Over which portion of the event does energy appear to be conserved?

o How would you explain portions of the graph where the total energy is not constant? (Note that “human error” is not a sufficient explanation. If you made a mistake, go back and collect your data over again.)
A PENDULUM
• Use Logger Pro to analyze the motion of the swinging pendulum.
• Create a graph of the potential, kinetic, and total energy of the ball as it swings to one side and back again.
• Take a screenshot of your graph and insert it below.
• Answer the following questions using your graph:
o Over which portion of the event does energy appear to be conserved?

o How would you explain portions of the graph where the total energy is not constant? (Note that “human error” is not a sufficient explanation. If you made a mistake, go back and collect your data over again.)

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