Purpose:  To demonstrate that the total energy of an object in free fall is constant.

Procedure:
1. You will be using the data you obtained in the free fall experiment. You can only use those dots for which you have a position and were able to calculate a velocity. It will be easier to handle the units if all distances are converted to meters, and velocities converted to m/s.

2.  The gravitational potential energy (U) is calculated from the height of each point above some specified `ground level'. We will define the ground level as the position of the lowest dot which has a velocity. As an example suppose I have a velocity at all dots from 3 to 15. By subtracting the position of dot 3 from the position of dot 15, I get the height of dot 3 above dot 15, h₃ = y₁₅ - y₃. I can also get h₄ = y₁₅ - y₄, etc..  Fill in the column marked h_n in the table in this manner for your data, making sure to convert to meters (m). Also fill in the column marked v_n with your data. Don't do any subtracting or rearranging on the velocities, just convert to meters per second (m/s) and transfer them.

3. Obtain the mass of the free falling object in kilograms (kg). For each dot calculate the gravitational potential energy (U), the kinetic energy (K), and total energy (E), in Joules (J). In the table I have used a mass of 0.5 kg, your actual mass will be different. Round these numbers to 3 significant figures before putting them into the table.

U_n = mgh_n     K_n = 0.5mv_n²     E_n = U_n + K_n

I highly recommend that you calculate U₃, K₃, and E₃ before you go on to dot 4, dot 5 etc..., this may save you from having to redo a lot of stuff, if you make a mistake.

4. Are all your E's the same (within some small experimental uncertainty)? Calculate the average energy E_ave from your table. Calculate the standard deviations of your data from E_ave. If one or two energy values are completely different from the others, and you cannot find any errors in your calculations, you may omit these bad values from your calculation of E_ave and s. If in doubt, ask for help. Note that s is an indication of the average deviation of each energy from E_ave, and that you square the differences before performing the summation. N represents the total number of points which you were able to use. Calculate the percentage deviation from E_ave.

% deviation = (s/E_ave) X 100

Specific
question: With what velocity does the corn popper jump off the table?

Procedure: Experiment with one of the poppers. Determine how much potential energy is stored in the popper before it pops. Determine the velocity of the popper immediately after it pops. Carry out whatever measurements you think are necessary.

Specific
question: What determines how high a ball bounces?