Students may wish to simulate a gravity-like force for their science fair experiments. Using a record player turntable is a convenient way to generate a centrifugal force as a substitute for gravity in the lab. Centrifugal force is an outward force that acts upon a mass that rotates about an axis.
Seedlings growing in the dark inside film cans provide good test subjects.
For these experiments it is useful to measure the magnitude of the centrifugal force on the plant. The magnitude of the centrifugal force exerted on an object depends on its angular velocity and distance from the center of rotation. For example, a 78 rpm turntable makes a good centrifuge for tropism experiments with seedlings in a classroom setting.