Proposal for Energy Principle

Abstract

The purpose of this experiment is to investigate the Energy Principle that we have learned in class. We propose an experiment with a tennis ball free falling from a certain height. The free falling motion will be recorded by a video camera. The video of the motion will be uploaded to Tracker software to obtain the x-component and the y-component of the location of the ball at each time instance. We will use Excel to calculate the velocity of the ball at these instances and then calculate the kinetic energy of the ball. After that, we compare the ball's kinetic energy to the energy from the surrounding, or energy due to the gravitational force. From the results, we should be able to conclude that the work from the force of gravity gets transferred into kinetic energy to the ball.

Background

According to Energy Principle, change in Energy of a system is equal to Work done by the surrounding. So Energy doesn't disappear, but is transformed into the Work done by surrounding. In this case, it's Work done by Gravitational Force.

Energy Principle:         E_f - E_i = W_surr

                                  K_f - K_i = W_surr

                                  K_f - K_i = (F_xΔx + F_yΔy + F_zΔz)

                                  1/2*mv_f² - 1/2*mv_i² = (F_xΔx + F_yΔy + F_zΔz)

With this experiment, we will test the validity of the above Energy Principle.

Procedure

1. Weight the mass of a ball, and the height the ball will fall.

2. Record video starting before dropping the ball from the measured height to the ground.

3. Upload video clip to Tracker software.

4. Use Tracker to find the time, x component, and y component of the motion.

5. Calculate the ball's velocity, and the force acting on the ball, in this case it is the gravitational force = mg

6. Calculate the ball's Kinetic Energy KE = ½*mv²

7. Calculate Work done by the ball when falling W=F*vertical distance y

8. Compare the Kinetic Energy to the Work of the surroundings on the ball

9. Graph Kinetic Energy vs. Work of the surroundings

The Investigator is responsible for making a step by step procedure for how to do the proposed experiment.  The procedure must be detailed enough so that a different group could follow it.  The Investigator is responsible for collecting data including the filming of the process, the calibration of distances and masses.  The quality control people (Skeptics) check that this has been done honestly. The data must be included in the appendix.

Preliminary Results

The video clip will be uploaded to Tracker to get the location for each instance.

With the x and y locations, we can use the following formula to calculate the velocity:

v_x = delta x / delta time

v_y = delta y / delta time

Next, we calculate Kinetic Energy K = ½*mv^2

Work only involves gravitational force in this case: Fy = mg.

Work done by Fy: W = Fy * delta x

We will then compare the results to see if Change in Kinetic Energy = Work done by gravitation.