Science Chapter 12

Periodic motion like a pendulum swinging is at a constant rate.

What is the difference between a periodic motion like the swinging of a pendulum and other repetitive motions, such as kids playing on a see saw?

Vibrations are very small rapid repetitive motions; oscillations are larger or slower repetitive motions.

Although they are similar and may overlap, what is the general difference between a vibration and an oscillation?

Vibration

When a string on an instrument is plucked, would you call that a vibration or an oscillation?

Gravitational potential energy (GPE) and kinetic energy

What two types of energy are converted back and forth with a pendulum?

Elastic potential energy, gravitational potential energy, kinetic energy

What three types of energy are converted back and forth with a spring suspending a weight?

Because right over the hole is its rest position

On a certain mini golf course, there is a log hanging right in the way of the hole. The sign says to swing the log before putting. When left alone on a still day, why will the log always stop right over the hole, instead of off to the side?

They will give the same amount of time because the only factors that affect the pendulum's period are the length of the pendulum arm and the acceleration due to gravity

Will swinging the log higher or barely swinging it give you more time to sink the putt between swings?

Amplitude

Swinging the log farther will change which property/properties of the pendulum?

Mass affects the period. A more massive object would have a longer time and therefore would have a smaller frequency

Why do guitar strings have different thickness?

Resonance

 I once had a car that would shake at certain RPMs. When accelerating quickly or cruising at 58 miles per hour it would start to shake and increase in bouncing until you were afraid the car would fall apart. Going slower or faster would not make it shake so bad. Later we fixed what was causing the shaking, but why did the shaking compound at a certain speed?

Damping

For resonance to happen, it has to overcome which force that weakens a periodic motion?

At a single point at the end

For an imaginarily perfect pendulum, where is all of its mass?

That the earth is rotating

What did the Foucault Pendulum prove until more direct evidence could be obtained by looking back at earth from the moon?

At the equator

Where in the world would a Foucault Pendulum not show a difference, even after swinging for several days?

It would swing in a different direction

How would a Foucault Pendulum at the south pole be different than a Foucault Pendulum at the north pole?

Mechanical energy

What is the primary thing moved by water waves?

Electromagnetic waves

What type of wave can carry energy without matter?

Period

When approaching the ocean, a child estimates the time between one wave coming and another coming. Which wave property is she looking at?

Sound waves travel faster in dense material

What was different about the earth's material in the Moho that caused there to be a difference in the speed of earthquake waves?

Pulse

What is a single wave or very short burst of waves?

Low energy

If a light wave has a high wavelength, does it have high energy or low energy?

The particles come together in compressions and spread apart in rarefactions.

What are the two motions on longitudinal waves that describe the particles getting closer together and getting farther apart?

Reflection

What wave phenomenon allows for sound to echo?

Refraction

What wave phenomenon might cause a fish in a tank appear in two locations at once?

Destructive interference

What wave phenomenon may make areas in a room where the echos off the wall add up to silence?

Constructive interference

Why do parabolic reflectors allow us to listen to sounds on the field that normal microphones can't pick up?

Doppler effect

What property of waves is used when tracking moving weather systems or determining the speed of a passing car?

The different waves have a slightly different period, which causes beats

Why did the pendulums sometimes seem to be going together and sometimes seemed to be going apart?

Diffraction

What wave phenomenon allows us to hear around a corner?

Doppler effect

What wave phenomenon causes an approaching siren to sound higher pitched than a siren traveling away? This is also why NASCAR race cars have a well-known sound effect.

US Naval Observatory in Washington DC

Where is the atomic clock that keeps the official time for the USA held?

Cesium

 What element does an atomic clock use that vibrates at a very specific frequency?

A pound of feathers weighs more because they use different systems. The Troy system and the avoirdupois ounce

What weighs more a pound of feathers or a pound of gold?

An ounce of gold.

What weighs more an ounce of gold or an ounce of feathers?

First Law of Thermodynamcis

What law allows periodic motion to happen by converting between the kinetic energy and the restorative force (such as GPE or EPE) without any being destroyed?

Any motion that repeats at a constant rate

What is periodic motion?

The point around which movement occurs

What is rest position?

The maximum distance from rest position the motion goes during each oscillation (units: usually any distance unit)

What is amplitude?

The amount of time it takes for one cycle to complete (units: any time unit, often seconds)

What is period?

The rate at which the cycles repeat. It is cycles per second, or 1/period. The unit for 1/s or s-1 is Hertz (abbreviated Hz)

What is frequency?

Periodic changes that transmit energy from one place to another

What are waves?

Electromagnetic waves

What waves transmit energy without matter?

The crest

What is the highest point of a wave?

The trough

What is the lowest point of a wave?

The midpoint between the crest and the trough

What is the rest position of a wave?

The distance from crest to trough. This is twice the amplitude

What is wave height?

The distance from one crest to the next crest (or trough to trough). It is abbreviated with lambda  λ

What is wavelength?

The number of waves that pass in a second (measured in Hz)

What is wave frequency?

In a vacuum

Where does light travel fastest?

The particle motion is perpendicular to the overall direction of wave travel

What is a transverse wave?

The particle motion is in line with the overall direction of wave travel. The particles come together in compressions and spread apart in rarefactions.

What is a longitudinal wave?

Refraction

What allows lenses to work?

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1. The spring is stretched, so it wants to restore to the rest position. This is elastic potential energy (EPE).
2. When released, the EPE is converted into kinetic energy upward.
3. At its rest position, the force of the weight downward is equal to the force of the spring upward. Its momentum carries it past that point.
4. The weight continues upward, storing energy as gravitational potential energy (GPE) until it reaches its highest point.
5. The weight falls back down, converting GPE into kinetic energy and then EPE, completing the cycle

Essay.