Oscillations

The springboard used in modern diving competitions is a complex mechanical system that a skilled diver must master. In a running dive, for example, a skilled diver knows how to first take three quick steps along the board to start the board oscillating and then leap to the free end of the board so as to be catapulted high into the air. A novice diver can imitate that procedure but fail miserably to be catapulted upward and might even be knocked off the board.

What is the “secret” of a skilled diver’s high catapult?

The answer is in this lesson.

What Is Physics?

Our world is filled with oscillations in which objects move back and forth repeatedly. Many oscillations are merely amusing or annoying, but many others are financially important or dangerous. Here are a few examples: When a bat hits a baseball, the bat may oscillate enough to sting the batter’s hands or even to break apart. When wind blows past a power line, the line may oscillate (“gallop” in electrical engineering terms) so severely that it rips apart, shutting off the power supply to a community. When an airplane is in flight, the turbulence of the air flowing past the wings makes them oscillate, eventually leading to metal fatigue and even failure. When a train travels around a curve, its wheels oscillate horizontally (“hunt” in mechanical engineering terms) as they are forced to turn in new directions (you can hear the oscillations).

When an earthquake occurs near a city, buildings may be set oscillating so severely that they are shaken apart. When an arrow is shot from a bow, the feathers at the end of the arrow manage to snake around the bow staff without hitting it because the arrow oscillates. When a coin drops into a metal collection plate, the coin oscillates with such a familiar ring that the coin’s denomination can be determined from the sound. When a rodeo cowboy rides a bull, the cowboy oscillates wildly as the bull jumps and turns (at least the cowboy hopes to be oscillating).

The study and control of oscillations are two of the primary goals of both physics and engineering. In this app we discuss a basic type of oscillation called simple harmonic motion.