In this issue:
A stretched rubber band is a great source of elastic potential energy. When released, that energy is converted to kinetic (motion) energy as the rubber band snaps back to its original size and shape. How can we tap into this energy source? Let's try using it to power a small car! (Adult supervision required.)
Buy our Balloon & Rubber Band Car Kit to get everything you need to build a rubber band car and a balloon car. Or, find the following materials:
The more you twisted the rubber band around the axle, the more potential energy you built up. When you let go, the rubber band snapped back to its original form, spinning the axle in the process. The potential energy in the stretched band was converted into kinetic energy propelling the car forward!
There are many ways you could change your car design to make it go faster or farther. Experiment with different types of wheels. Will the car go farther if you use bigger wheels, or wheels with more or less friction? What if you use bigger wheels in the back and smaller in the front? Or a 3-wheeled design? Try building a car with CDs for wheels. Does the weight of your car affect how it travels? Try adding a load like coins or washers to the car and see how it changes the distance or speed. What happens if you make your chassis longer? If you give your car a ramp to start on, how much further will it travel?
Try building two cars with different features and race them against each other!
Physics Car Experiment Kit
This exciting car kit has everything you need to build and experiment with multiple car models! Design and build a balloon car, mousetrap car, solar car, and rubber band car. As you build, you'll learn about different methods of propulsion and experiment with multiple design features. The materials in this kit allow free reign to your creativity: you'll get various sizes of wheels and axles, a motor, gears, solar cell, balloons, mousetrap, and more. Includes instructions for building several different models.
Try this very simple project to create a floating disc that skims across a surface similar to the way an air hockey puck or hovercraft does.
A hovercraft works by forcing air out beneath it, creating a cushion of air to float on. Hovercrafts usually have a "skirt" that surrounds the base to contain the air; in this project the CD is light enough that it doesn't need a large cushion, so no skirt is necessary. The balloon acts as a pressurized gas chamber. When you open the cap, the balloon forces air out through the cap, creating a thin cushion of air beneath the CD.
As you nudged your hovercraft around, you may have noticed that it zipped along the surface like an air hockey puck. That's because air hockey uses the same principle, with the puck floating on a layer of air. In the case of an air hockey table, the air is forced out from the table below rather than a source above like a hovercraft. Try pushing a plain CD across the table, and then your hovercraft. Do the two move differently? That's because the thin cushion of air from the hovercraft reduces the friction between the CD and the table. Because of the reduced friction, hovercrafts can reach higher speeds.
The first operational hovercraft was invented by Sir Christopher Cockerell, who successfully crossed the English Channel in one in 1959.
Since water is denser than air, there is more friction on objects moving through it. Fish have streamlined bodies to reduce the friction between them and the water.
Learn about force and momentum with this entertaining animated lesson.
Reenact Joe Kittinger's 1960 "skydive from the stratosphere" in this online game to learn about air friction.