Rubber Band Cannon
Super Value Laboratory Kit
Materials Included In Kit
Cannon aiming sticks, 8
Cannon bases, 8
Printed Protractor Master*
Rubber bands, thin, 15
Rubber bands, thick, 15
Screws, washers and wing nuts, 8 each
*See Prelab Preparation.
Additional Materials Required
Glue or transparent tape
Safety glasses or goggles
Make enough copies of Printed Protractor Master (see Teacher PDF) for each group.
Safety glasses must be worn by everyone during this entire laboratory. Do not aim the Rubber Band Cannon at anyone. The cannon firing should be conducted in an open area such as a gymnasium, cafeteria or outside.
All the materials should be saved for future use.
- Enough materials are provided in this kit for 24 students working in groups of three or for eight student groups. All materials are reusable. The laboratory activity can be completed in one 50-minute class period, but several class periods may be needed if additional experiments or contests are performed.
- The distances the rubber bands travel typically have a wide range. They are significantly affected by air resistance and air currents. Additional trials may be performed for each experiment. Then, high and low values can be ignored when calculating the average values. Several practice launches should also be performed until students are comfortable with a launch technique.
- The Rubber Band Cannons can be built prior to the lab in order to save time.
- Since there may be up to eight Rubber Band Cannons in operation at the same time, a large arena will be necessary. Safe areas to fire the cannons include a gymnasium, cafeteria, hallway, empty classroom or outdoors. Determine a suitable location before the laboratory activity.
- This activity will generate considerable excitement and noise. It might be wise to conduct test-firing in the gymnasium or outside. Inform your colleagues if you are going to perform this activity in the common school hallway so as not to disrupt other classes, especially if the other classes are taking exams. Performing this activity outside the building introduces additional variables including wind direction, wind velocity, temperature, humidity, etc. If the activity is expanded, students may identify additional key variables and design controls to test these variables.
- In this activity students will fire rubber band projectiles over several meters. Be sure that all safety precautions are followed during this activity. Safety glasses or goggles must be worn at all times by everyone in the area of the Rubber Band Cannons.
- The key idea of student experimentation is to learn to identify and control variables one at a time so that cause and effect can be inferred. This is the basis of the scientific method. Emphasize this throughout the activity.
- If students are interested in learning more about how to predict projectile ranges, refer them to any physical science or physics textbook, or the Internet, such as http://hyperphysics.phy-astr.gsu.edu/hbase/hph.html (accessed October 2011).
- If the room is large enough, use four launch positions at the center of the room, separated by 5 or more feet, with two groups at each position. The two groups at each launch position will fire their cannons in opposite directions so that four of the groups will fire one way and four groups will fire in the completely opposite direction. This should help to optimize the available space and improve safety.
- Predict a combination of variables that will allow the Rubber Band Cannon to hit a target four meters away. Test your prediction. Is there more than one way to shoot the rubber band this distance?
- Prepare a “firing table” that shows how different variable combinations may work best for different distances. Test the firing table.
- Set up a contest to determine the most accurate firing table. The range officer (teacher) will set up a firing line and a target distance. The target will be a 25-cm diameter circle.
- Each group has three warm-up shots and three official shots.
- The target will be placed on the floor two to four meters away from the firing line, but only the range officer will know the distance before the contest begins.
- The group who hits the target with the most shots is the winner.
- If there is a tie, the target distance will be changed and the groups that are tied will have a shoot-out.
- How did the firing table help in predicting the proper variable values needed to hit the target? How could the firing table be improved? Were there other variables that were not included in the firing table that may have helped to hit the target more often?
Correlation to Next Generation Science Standards (NGSS)†
Science & Engineering Practices
Planning and carrying out investigations
Analyzing and interpreting data
Using mathematics and computational thinking
Disciplinary Core Ideas
MS-PS2.A: Forces and Motion
HS-PS2.A: Forces and Motion
HS-PS3.A: Definitions of Energy
Scale, proportion, and quantity
Energy and matter
Structure and function
Stability and change
Rubber Band Variable
Answers to Questions
- How does changing the angle variable affect the distance of the shot?
As the angle increases, the distance the rubber band travels also increases up to a point. The maximum distance is achieved at an angle of 45°.
- How does changing the stretch variable affect the distance of the shot?
The more the rubber band is stretched, the longer the rubber band travels.
- How does changing the rubber band variable affect the distance of the shot?
The thin rubber band travels farther than the thick rubber band. This is true when both are stretched a short distance and when they are both stretched a long distance.
- Why do you believe one rubber band traveled a greater distance than the other (all other variables being constant)?
The thicker rubber band did not travel as far as the thinner rubber band. This may be the result of increased air resistance on the thicker rubber band. The air resistance slowed down the thicker rubber band more quickly than the thin rubber band. It was observed that the thick rubber band tended to travel a certain distance and then appear to just fall straight down. The thin rubber band traveled in a more curved path. Also, the thin rubber band seemed harder to stretch than the thick rubber band. So at the same stretch distance, the thin rubber band will supply more force (thrust) as it relaxes back to its original shape. Therefore, the thin rubber band had a faster launch speed than the thick rubber band.
- What other variables could be tested that might affect the range of the rubber band cannon?
Wind or air currents affected the path of the rubber band. The difference between the initial length of the rubber band and the stretched length could be tested. The height the rubber band is actually launched at is also a variable that was not tested.
- How might the rubber band cannon improve its range?
A smoother release mechanism might help improve the accuracy of the Rubber Band Cannon. The rubber band has a tendency to get hung up on fingertips as well as on the launch stick. Thinner rubber bands tend to fly farther which may be the result of less air resistance, so even thinner rubber bands may fly farther.
Sample Firing Table