The Great Bungee Jump
Now we time accurately how long it takes the mass to fall through different distances. You should now have a working bungee drop with an accurate timer that can do this. Now you are ready to start getting data for the model bungee jump.
Step 4: Getting Data The Bungee Experiment
1. Set up the jump. Tie one end of about 1.5 meters of bungee elastic cord to your lead sinker mass. Be sure that it is firmly tied and will not slip while you experiment. You may want to tie two knots to make sure the cord will not slip.
The purpose of this investigation is to see if a full-sized bungee jumper could escape from a burning skyscraper. To make your model represent this, you need to adjust the length of the bungee cord so that your "jumper" nearly touches the ground. Experiment with the length of the elastic until your model works right, then tie the cord firmly to the top of your tower. Duct tape wrapped around the knot helps avoid slipage.
2. Measure the height, mass, and spring constant. Later, you will need to know some numbers for your particular model. These include its height, how much mass you have and how much "spring" your bungee cord has. Record these values:
- The height, in meters, above the ground of the mass when it is released. Measure the height to the bottom of the mass.
- The height, in meters, above the ground of the mass when the bungee just becomes taught and starts to pull.
- The height, in meters, above the ground of the mass when it is just hanging from the bungee cord and is at rest.
- The mass, m, of the lead sinker, in kilograms.
3. Predict your results. Before taking data, try to predict what your results will look like. Drop the mass several times and watch carefully what happens. Make three sketches using vectors to show the forces acting on the mass:
Sketch a graph of what you think the velocity of the mass will be at different times. Remember that the mass is not moving when you release it. It is also not moving at the very bottom of its drop. Discuss your graph with your group and your teacher. Use this velocity graph to sketch a graph of the height of the mass as a function of time. Use the velocity graph to sketch a graph of the acceleration of the mass as a function of time.
- Immediately after it is released
- About half way down
- At the bottom of its fall.
Measure the time it takes the mass to fall through ten evenly-spaced heights. For each height, make several voltage...