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Students will apply the law of conservation of energy in a laboratory setting and perform a series of calculations including calculating work, kinetic energy, and potential energy.

This lesson assumes that students have been exposed to the concepts of work, energy, the law of conservation of energy and the calculation of physics problems dealing with work, kinetic energy and potential energy. Students should also know how to calculate the velocity of a marble at a single point along a ramp.

—Lesson Submitted by Troy Schuknecht

You Will Need

One ramp that will allow a marble to roll in a straight line. (I have used molding from a lumberyard as you can usually find a pattern perfect for a marble.)*

One milk carton with the top removed*

Three marbles (one metal, one plastic, and one glass)*

A ruler*

6 books (or something to prop up the ramp and give it a slight angle)*

Describe the transfer of energy throughout the following scenario. Show students the PowerPoint Presentation: Energy Pre-Lab (which illustrates the lab apparatus to be used in this lesson).

Provide procedural instructions for the lab and demonstrate the laboratory technique. The PowerPoint slides also show the technique for students.

Students conduct the lab, take data, make calculations, fill out the data analysis section, and form conclusions (see lab sheet for more details).

Students answer the learning questions on the backside of the conservation of energy practice sheet.

Go over the questions.

Ask a new question and have students design their own experiment to test it as their homework. The follow up question is "How does the mass of the marble affect the work done on the milk carton?"

Let students know that they should return the following day with their experimental procedure complete.

Day 2

Check to see who completed their experimental procedure for homework.

Give lab groups a few minutes to review each students attempt at a procedure and decide whose they want to try.

Instruct students to run their lab. This would be a great lab to have written up as a formal lab report or you can collect a more informal write-up.

Wrapping Up

Ask students if they believe that the work they did to lift the marble each time to the top of the ramp was exactly equal to the work done on the milk carton. (Hopefully they will bring up the notion of energy being converted to heat because of friction).

Have students use the Vernier Video Physics app to film the metal marble moving down the ramp. Note: The iPad must be fixed and you need to place a ruler on the edge of the ramp clearly visible by the iPad camera. Then follow the instructions to graph the marble.

After estimating the kinetic energy of marble at the bottom of the ramp assuming that there is no friction (it would be the same as the potential energy at the top of the ramp), use the velocity-time graph produced by the app to estimate the velocity of the marble at the bottom of the ramp.

Use this velocity to calculate the actual kinetic energy using the formula.

Repeat this process with the plastic and glass marbles and use the difference between estimated and actual kinetic energy to determine which marble had the most friction on the ramp.