Imagine picking up a lightweight suitcase and feeling the case fight your efforts to carry it down the street. By mounting a bicycle wheel in a suitcase so that it is free to spin when the suitcase is closed, students can begin to understand the physics of rotating objects. An older, hard-shell suitcase would have to be adapted to hold the wheel and allow it to rotate when the case is closed. Students should modify the top of the case so that a flap can open and close when the case is still in the closed position. After mounting the wheel in the suitcase, start it spinning, close the case and then invite a student to pick up the case and carry it across the room. As the case changes direction, the forces created by the hidden, rotating wheel will cause the suitcase to act as if it is attached to unseen guide wires.
A simple experiment demonstrating the physics of a rotating gyroscope involves a bicycle wheel and a rotating barstool. Have a student sit on a stool which rotates freely, holding a bicycle wheel at arm's length. The teacher spins the wheel, and as the student tilts the wheel's axis of rotation, the barstool will begin to rotate in the opposite direction. This phenomenon demonstrates Newton's second law of motion, which says that every object acted upon by an outside force -- in this case, the student -- creates an equal and opposite force acting in the opposite direction. The force created by changing the orientation of the rotating wheel is counteracted by the rotation of the barstool.
Simple toys, such as a gyroscope sold in a toy store, can illustrate the physical forces created by, and acted upon, by moving objects. In the classroom, start a toy gyroscope spinning at high velocity and then place the toy top on the edge of a heavy, glass container, such as a quart mason jar filled with sand. If the top is placed on the rim of the container so that the top's rotational axis is parallel to the floor, the top will remain suspended in mid-air as long as it spins at high speeds. As the top slows down, it will succumb to gravity and fall off. This experiment is a launching pad to discuss gravity, friction, rotational inertia and centrifugal forces.
Another experiment for gyroscopes requires a counter-poise gyroscope. This device features a traditional gyroscope attached to a long, rigid shaft. The shaft is fitted with an adjustable counterweight, which slides along the shaft. When the gyroscope starts to spin, it is balanced on a stand at a point along the shaft, between the gyro and the counterweight. When the device is perfectly balanced by sliding the counterweight along the shaft, the gyroscope remains stationary. When the counterweight slides toward the spinning gyro, the entire device rotates clockwise. If the counterweight is moved away from the spinning gyro, the device rotates in the opposite direction. This experiment visually demonstrates how the rotational forces created by the gyroscope respond and react to outside forces acting upon it.