Lab Energy of the Tossed Ball
Procedure:
- Measure and record the mass of the ball you plan to use in this experiment.
- Connect the Motion Detector to the DIG/SONIC 1 channel of the interface. Place the Motion Detector on the floor and protect it by placing a wire basket over it.
- Hold the ball directly above the Motion Detector. Have your partner click to begin data collection. Toss the ball straight upward above the Motion Detector and let it fall back toward the Motion Detector catch the ball before it hits the detector.
Note: Use two hands, be sure to pull your hands away from the ball after it starts moving so they are not picked up by the Motion Detector. Throw the ball so it moves vertically above the detector. Verify that the position vs. time graph corresponding to the free-fall motion is parabolic in shape, without spikes or flat regions, before you continue. This step may require some practice. If necessary, repeat the toss, until you get a good graph. When you have good data on the screen, proceed to the Analysis section.
- Click on the Examine button, , and move the mouse across the position or velocity graphs of the motion of the ball to answer these questions.
- Identify the portion of each graph where the ball had just left your hands and was in free fall. Determine the vertical position and velocity of the ball. Enter your values in your data table. (after release)
- Identify the point on each graph where the ball was at the top of its path. Determine the time, vertical position, and velocity. Enter your values in your data table. (top path)
- Find a time where the ball was moving downward, just before it was caught. Measure and record the vertical position and velocity of the ball at that time. (before catch)
- Collect two more times on the way up and on the way down for a total of seven data points.
- For each of the seven points in your data table, calculate:
Gravitational Potential Energy: Ug =mgy ; Kinetic Energy: K = 1/2mv2 ; and
Total Energy: TE = Ug+KE
