Physics – Conservation of Energy LabName: ______

Kowinsky

Conservation of Energy Lab

Purpose:

The initial energy put into a system is equal to the energy given out by the system:

Energyin = Energyout

This statement is called the law of conservation of energy. The purpose of this lab is to study the law of conservation of energy by experimenting with 3 simple machines; the inclined plane, the fulcrum, and the pulley.

In real life situations, friction exists. Friction always decreases the useful energy output of a system:

Workin = Workout + Waste Energy

In this lab, you will also calculate the efficiency of these 3 simple machines.

Simple Machines:

There are 7 basic simple machines; a pulley, lever, wheel and axel, fulcrum, wedge, an inclined plane, and a screw. A simple machine does not reduce the amount of work a person needs to do. Instead, it reduces the amount of force a person needs to apply by increasing the displacement the person needs to apply the force over.

Procedure:

Your lab group is to measure the work (energy) put into the system for each of the 3 simple machines. Work = Force x Displacement. Therefore, your group needs to measure the force you put into the machine and the displacement you put into the machine. After measuring the work put into the machine, your group is to measure the work done by the machine. The output work is equal to the output force times the output displacement. Next, calculate the efficiency of your machine. Record your findings in a chart similar to the one below:

Inclined Plane / Fulcrum / Pulley
Trial 1 / Trial 2 / Trial 3 / Trial 1 / Trial 2 / Trial 3 / Trial1 / Trial2 / Trial3
Fin (N)
Xin (m)
Fout (N)
Xout (m)
Win (J)
Wout (J)
% Efficiency
(Wout /Win )

Finally, calculate you average efficiency for the 3 machines:

Inclined Plane / Fulcrum / Pulley
Average % Efficiency

Conclusion:

According to the law of conservation of energy; Energyin = Energyout ; Workin = Workout + Waste Energy. Because of friction, your efficiency should never be equal to 100%. In your conclusion, discuss how close your values of Win and Wout were. Discuss the sources of friction for each of the 3 simple machines used. In what ways was waste energy given off for each machine? What other factors contributed to errors in this experiment? Pay close attention to the errors with the fulcrum. Address these questions in the conclusion of your lab report.

______

Rubric

Conservation of Energy Lab Write Up

20 points total

______2pts. Typed – The Lab Write up should be typed (equations, calculations, and graphs can be hand written)

______2 pt. Title Page - should include the title of the lab and group member names

______3 pts. Introduction – This should contain the purpose (what you are trying to find, verify, examine, etc..) and a general description of the lab. It needs to introduce new terminology (Simple machine, efficiency, etc..) The introduction should not be 1 or 2 sentences, it should be a well developed paragraph or two.

______4 pts. Procedure – A detailed, step by step, explanation of the materials used, and how they were set up. This should be clear enough so the experiment could be reproduced by anyone who reads your procedure.

______5 pts. Analysis – This section should contain all of the data and calculations needed for the lab. The data measurements need to be recorded in proper units. For the calculations, all applicable formulas and data tables need to be listed and explained, and the calculations should be worked out AND explained.

______4 pts. Conclusion – The conclusion ties into the purpose of the lab and tells the reader what was found. Experimental data from the analysis should be included to support the conclusion.

Sources of error need to be listed. The error needs to be calculated if applicable. The sources of error need to reflect involved thought processes and deep understanding of the experiment. It should also contain an explanation of how the error was caused, and how the error could be minimized in the future. Also address the questions given in the lab procedure sheet.

TOTAL:______out of 20 pts