Box of Many Balls
| Physics: | Energy Transfer, Collisions |
| Grade Range: | Elementary School, Middle School |
| Format: | Hands-on |
This is a good demonstration for keeping kids occupied, and it is for students to try and learn what is happening on their own. Steps one and two can be put onto a placard, while steps three and four can be done by the presenter periodically throughout the event.
Materials
- Bouncy Ball
- Soccer Ball or Basketball
- Metal ball
- Tennis Ball
- Ping Pong Ball
- Hacky-sack Ball
- Box to Hold Them
Safety Precautions
Please read the General Safety section of the Demonstration Safety page before performing this demonstration.
Demonstration
- Allow students to roll the balls into each other. Don’t let students throw the balls! What balls bounce off of each other? What causes them to bounce off of each other?
- Let the students try dropping the bouncy ball, the metal ball and the hacky-sack ball at the same height. Which one bounces the highest? Which one bounces the lowest, or doesn’t bounce?
- Hold the basketball or soccer ball up with one hand, and hold the tennis ball right above it. Ask the students for ideas on what might happen if you drop them at the same time. Proceed with the demonstration. The tennis ball will go flying!
- Repeat step three, but hold the tennis ball underneath the other ball this time. Ask for ideas on what might happen. Proceed with the demonstration.
Why This Works
Collisions are an introductory topic in physics, and start with a simple question: is the collision elastic or inelastic? Inelastic collisions are when the two objects collide, and they do not separate. An example of this is having the metal ball run into the sand-filled ball. Elastic collisions are when two objects collide, and they bounce off of each other. and example of this is when the tennis ball bounces off the basketball or soccer ball. In every type of collision there is an energy transfer happening between the colliding objects. For an inelastic collision, this means that the two balls combine their energies, and so they stay together because of it. For an elastic collision, the energy is transferred between balls, meaning that they “trade” energy. When we dropped the tennis ball above the bigger ball, the energy from the big ball was transferred into the tennis ball, and sent the tennis ball flying! When we did it with the tennis ball underneath, the energy of the big ball was transferred downward, which sent the tennis ball ricocheting!
Additional Information
- This demonstration pairs well with the Potential and Kinetic Hot Wheels.