pendulums are popular with both scientists and occultists.
Pendulums are simple devices consisting of a weight hanging on the end of a stream or pivoting beam. If you pull the pendulum away from vertical, it builds up potential energy. When you release it, that potential energy converts into kinetic energy, sending the pendulum swinging to the other side, which converts the energy back into potential energy. A perfect pendulum will keep swinging back and forth forever, but real pendulums lose some of their energy to wind and mechanical resistance, gradually slowing them to a stop. Pendulums are a favorite of science teachers who use them to demonstrate principles of physics. They are also popular among fans of the occult, who attribute mystical powers to them.
Conservation of Energy
Use a pendulum to demonstrate the conservation of energy in an amusing and striking way kids aren't likely to forget. Hang a pendulum on a long string in the center of the room. Pull the pendulum to one side and have a student volunteer stand so that the pendulum is right in front of his eyes. Ask if he believes in the conservation of energy (the scientific rule that states that energy is neither created nor destroyed.) If he says yes, tell him to stand still and release the pendulum. The student will probably flinch as the pendulum swings back towards him. If he does, demonstrate the activity yourself, staying still and allowing the pendulum to swing back toward you. The pendulum will stop slightly below your face. Explain that this is because of the conservation of energy. The pendulum, powered by gravity, can not swing higher than the point it started at because that would require it to develop extra energy.
Period
Pendulums are simple and easy to work with, making them great objects for scientific experiments. Supply your students with a number of pendulums on strings with different weights. Have the students predict how long a particular pendulum (say a one-gram pendulum on a six-inch string) will take to swing all the way across and back to its starting point. Ask them what effect they think doubling the weight or doubling the length of the string will have on the period. Have each student write a prediction, then time pendulums with different weights at several different lengths with stopwatches. Based on the results, have each student revise his theory.
Divination
Pendulums aren't just popular with scientists; since time immemorial, the pendulum has been used for divination. Establish a code for your pendulum based on the direction it swings. For example, forward and back means yes, left and right means no, clockwise means ask again later and counterclockwise means rephrase the question. In a clear voice, ask if there are any spirits in the room. When the pendulum answers "yes," use it to ask the spirit various questions.
You can also use the pendulum for dowsing with a similar code. For example, you can instruct the pendulum to turn clockwise if there is water in front of you, counterclockwise if there is not and to swing forward and backwards if there is water directly underneath you. Go to the spot you want to dowse, turn around in a circle until the pendulum starts to turn clockwise and follow its signal until you find a spot with water.
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