Skateboards: Simple Machines

INTRODUCTION

A wheel and axle is a simple machine that is actually a modification of a pulley. Like the pulley, the wheel and axle makes work easier by reducing friction. The wheel and axle must function together to be a simple machine.

MATERIALS

• Skateboard
• Group of at least 3 students
• Flat and smooth floor surface

WHAT TO DO

1. Place the skateboard wheel-side-up on the floor. Ask one student, the rider, to stand on the skateboard.
2. Choose another student in the group to be the mover, the one who will apply the force. All other students in the group will be protectors, making sure that no one will fall during the experiment.
3. Instruct the mover to push on the skateboard to try to move the rider 2-3 feet across the floor while the protectors help stabilize the rider.
4. Ask for observations from all students in the group.
5. Turn the skateboard over so that the wheels are in contact with the floor. Instruct the same rider to stand on the skateboard.
6. While the protectors provide stability for the rider ask the mover to again push the skateboard to try to move the rider 2-3 feet across the floor.
7. Share and discuss observations.

QUESTIONS

1. Was it easier for the mover to move the rider when the skateboard was placed wheel-side-up or wheel-side-down? Why?

SUMMARY

The wheel and axle is a simple machine that reduces friction to make work easier. Students will have a much easier time moving their classmates on a skateboard with wheels down than with wheels up!

SOURCE

"Marbles, Roller Skates, and Doorknobs: Simple Machines That Are Really Wheels." Christopher Lampton. Millbrook Press, Brookfield: 1991. ISBN: 1-878841-24-6.

© S. Olesik, WOW Project, Ohio State University, 2003.