Have you ever stretched a rubber band and launched it? Put that energy to use and build a rubber band–powered cotton ball launcher in this fun activity!
When you stretch a rubber band it stores elastic potential energy—the energy stored inside a material when it is stretched, squished, bent or twisted. This is different from gravitational potential energy, which is stored in an object that is lifted off the ground. Both types of potential energy can be converted to kinetic—the energy of motion. All moving objects have kinetic energy, but motionless ones have none. When energy is converted between forms the total amount of energy remains the same. In other words, it is conserved. (Some energy, however, may also be converted to heat due to friction—but that is still a form of energy.)In this activity you’ll explore conservation of potential and kinetic energy by measuring the distances you can launch a cotton ball using your own homemade launcher!
In this activity you used two types of energy to load and launch your cotton ball. As you drew back on the pencil with the cotton ball loaded you were adding potential energy to the system. The farther you pulled back on the pencil, the more potential energy was being stored. When you released the pencil, the energy became kinetic and the cotton ball should have gone flying through the air!
The farther you pulled back on your launcher the more potential energy you added to the system—and the more you stored the more kinetic energy should have been released when you shot the cotton ball. As a result, the farther you pulled back on the launcher, the farther the cotton ball should have traveled.
This experiment was selected for Science at Home because it teaches NGSS Disciplinary Core Ideas, which have broad importance within or across multiple science or engineering disciplines.
Learn more about how this experiment is based in NGSS Disciplinary Core Ideas.