The pendulum experiment demonstrates how an object loses kinetic energy when seemingly no forces interact with the moving object. Begin by tying a sting to an apple stem. Next, tie the loose end of the string to a stick. Have a student stand directly against a wall while holding the tied apple to his or her forehead. Another student must hold the stick so the string is pulled tightly. Allow the student to let go of the apple and remain in position. While the student and the rest of the class think the apple might hit the student in the forehead when swinging back, this cannot happen. The apple loses kinetic energy due to the pull of gravity and air friction. Thus, the apple never returns to the same heights and eventually loses all kinetic energy.
Galileo famously tested the idea that heavier objects fell faster by dropping two different-weighted iron balls from the top of the Leaning Tower of Pisa. Of course, he proved that all objects fall at the same rate (debunking hundreds of years of scientific thought). Duplicate this project by holding two different sized balls (i.e. one basketball and one tennis ball) from the top of a ladder. Next, drop the two balls and record which one hits the floor first. Continue the experiment using different combinations of sports balls to see if the results vary. This experiments demonstrates that different sized object have similar kinetic energy, when dropped from a high distance, due to the pull of gravity.
The collision experiment demonstrates how objects can transfer kinetic energy to each other. Begin by placing a sponge at the bottom of a ramp. Next, let go of a small toy car at different heights on the ramp. Record how far the sponge moves with each attempt. The sponge moves farther as you increase the car's ramp height. This occurs because the extended period of time on the ramp allows the car to convert more potential energy into kinetic energy. This, in turn, gives the car more energy to transfer to the sponge as translated by the sponge's increased ability to move forward.
The friction experiment illustrates the affect surfaces have on kinetic energy. Construct a ramp with several different surfaces by gluing on a strip of carpeting, a strip of tin foil, a strip of sand paper and any other material you can find so long as each surface has a different texture. Next, drop a car from the top of the ramp and record the time it take to reach the bottom. Repeat for all surfaces on the ramp. Your results show that surface directly affects the car's ability to move downwards. This occurs because the car's kinetic energy must work against the ground's pull in the opposition direction, otherwise known as friction. Rough surfaces have greater friction than smooth surfaces. As such, the car has slower times on carpeting and sand paper than on tin foil or wood.