# Regents Physics

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## Singing bowls

Tibetan singing bowls are similar to humming crystal glasses. A mallet is used to vibrate the metal bowl by sliding along the edge in a circular motion. This creates a standing wave. The bowl acts as a resonating chamber, each edges' wave reflects off of the opposite side; which gives it it's unique sound. If the person controlling the vibrations does it gently enough and at the correct speed, the frequency remains constant while the amplitude will most likely increase. An increase in the speed

## How a plane flies

There are four main forces acting upon a plane which controls the way it flies. Lift is when is moves upward, as opposed to the gravity which pulls it downward. Thrust is when is moves in a forward direction, which acts against the force of drag (which is when air resistance pulls it backward.) In order for a plane to become airborne, its force of life must be greater than the force of gravity (9 m/s^2 on Earth.) Also, the propellers must thrust it in the direction it wants to go with a greater

## Concert physics

With my chorus concert tonight, it was brought to my attention (by Mr. Fullerton) that there is, of course, physics involved in how sound is amplified at concerts. Behind the musicians at a concert, there is a sound shell. Why is it there? It helps amplify the music for the audience. This works by acting as a barrier for the sound waves. The sounds waves travel in all directions, including towards the sound shell, and is reflected towards the musicians and the audience. This not only allows the

## Guitar String Resonance

When one plays a guitar, they are pressing down on the strings. Pressing down on different places on the string causes changes in tension, therefore changing the medium. When the medium is changed and you pluck the string, thereby creating a pulse, there is a change in frequency. The change in the frequency of the wave is what causes the string's audible change in pitch. Depending on the pattern of the pulses and the frequency of the string, the string becomes a standing wave. When the natural

## Salt vs Fresh Water

The speed of a wave depends solely on the medium. It is common knowledge that sound travels faster underwater than through air; but, contrary to what logic tells us, sound also travels faster through salt water than through fresh water. Usually, the rule of thumb is that sound travels slower in a denser medium of the same phase. But why would sound travel faster in salt water if it is denser? It's because of the difference in bulk modulus. "The bulk modulus of a substance measures the substanc

## Thunder and Lightning

In a thunder storm, lightning always comes first, because the speed of light is faster than the speed of sound. There's a trick commonly used to find how far away you are from the lightning during a storm. When you see the flash of lightning, you begin to count. You continue counting and stop when you hear the thunder. Let's say you count to ten. Then you are supposedly ten miles away from the lightning. The common misconception is that each second represents one mile of distance between you and

## Applying the Doppler Effect to water

The Doppler Effect is the change in wave length caused by motion. The classic example is the sirens on fire trucks and ambulances. The Doppler Effect is responsible for the change in the pitch of the siren as it speeds by. The way it works is the sirens are producing sound waves. When the truck moves, the distance between the waves is reduced, causing them to "bunch together" and travel at a higher frequency. This concept can also be applied to water. The current in a pool or a pond usually

## The physics of rainbows

No one can deny the awe felt when seeing a rainbow. The refraction of white light through prisms is a fascinating topic. It's easy to understand that light can be separated into the six colors of rainbow-red, orange, yellow, green, blue, and purple. But how exactly does it work? When light is shined through a prism, the energy of the light is absorbed by the atoms of the material. If the frequency of the light wave doesn't match the frequency of the vibrating electrons, the energy is reemitted

## Law of Sympathetic Resonance

Anyone who has experience with tuning string instruments understands the concept of the Law of Sympathetic Resonance. Wikipedia explains it like this: "Sympathetic resonance or sympathetic vibration is a harmonic phenomenon wherein a formerly passive string or vibratory body responds to external vibrations to which it has a harmonic likeness." To put it in simpler terms, it's when two tones are played at the same time and one can hear the sound waves beating off of each other. The smaller the in

## Orbits and Climate Change

While learning about orbits in physics, we were told that, "a force, such as gravity, pulls an object into a curved path as it attempts to fly off in a straight line." I'll use Newton's analogy for further elaboration: let's say a canon were to be fired off the top of a very tall mountain. Since projectiles have a parabolic trajectory, the cannonball would go up, stop briefly, then come back down. But, depending on the velocity at which it is fired, the cannonball would go up, and try to come ba

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