Physics Test - Vibrations/Wavelength

KNOW TERMS AND EXAMPLES

What is the type of graph that has radio waves, gamma waves, UV waves, microwaves, X-rays, etc?

Electromagnetic spectrum

When a siren is coming to you versus going away from you, the sound either increases or decreases, what is this called?

Doppler effect

2 Examples of a Sonic Boom

a Whip, a super sonic jet

You are sitting in room with open door, and someone leaves and closes the door, and another door slams shut by “a ghost”. What is it called?

Rarefaction - a vacuum is created, so air molecules move away

Sound below 20 Hz

Infrasonic

Waves created by movement

Bow waves 

What 2 things effect pendulum period?

Gravity, length of pendulum

What is the equation for speed of a wave?

Wavelength x frequency

What are 2 things that the Doppler Effect affects daily/scientifically?

Weather and Space (universe always expanding)

Also cars, and police sirens

What is the speed of wave that has wavelength of 4 m and frequency of 2 Hz?

8 m/s

What is the average speed of sound in the air that we utilize in the world?

340 m/s 

When you hear a thump from 2 or 3 different instruments that create that beat, what are we experiencing from what is creating that beat?

Constructive interference - overlapping 

3 examples of different people who NEED noise canceling headphones

Sensitive people (people who have autism, etc), construction workers, pilots, warehouse workers, people who work with machines

What is it called when we equal a forced vibration with neutral frequency?

Resenence 

330 m/s is speed of air in what situations 

Dry air at 0 degrees Celsius 

What shape does a typical wave through the air create if graphed?

Sine curve 

When you hear jet plane pass overhead, why when you look straight up is the jet not there?

Light travels faster than sound

What two things can be tuned in to match natural frequency?

AM and FM radio 

Period

How long it takes for object to go from one spot to the corresponding spot (one complete cycle of movement)

What are 2 kinds of waves did we discuss based on shape?

Transverse - the particles of the medium move perpendicular (at a right angle) to the direction the wave is traveling

Longitudinal - the particles of the medium vibrate parallel to the direction the wave travels

What causes a dead spot? 

Destructive interference

What color do we see shifted that indicts it is moving away us?

Red

Example of danger of resonance 

Bridge collapsing 

What is Constructive interference?

when two or more waves combine and their amplitudes reinforce each other, resulting in a wave with a larger amplitude (adds together)

Sonar in boat to find fish and a big whale swims underneath, and it takes 10 seconds to hit the whale and come back, if it is traveling 100m/s how far is it away?

500m (half distance away)

What is the bottom most portion of a curve?

Trough 

4 ½ waves past point in a second what is frequency?

4 ½ Hz

Besides period, what could we call 

Wavelength

What can be described as a “Wiggle in time”?

Vibration 

Long wavelengths have what type of frequency?How would we describe a pitch created by that wave?

Low frequency

Low pitch 

When playing with jump rope, if you start to do it to where your jump rope is creating 2 curves, what is it called at the middle? 

Node

When boats are passing us in teh water, the energy of the wave is passing in one dimension, what is it called when it passes in multiple dimensions?

Shock wave 

What do we call a sound that is above 20,000 Hz?

Ultra sonic 

When someone walks intoa  room with inward opening door, and the drapes go out the wind?

Compression (opp. Of rarefaction)

What two things are going to play a big role in natural frequency of an object?

Elasticity (material it is made of) and shape

Who died when tomacoco bridge collapsed?

A dog 

What do you call instrument that can tell us intensity of a sound?

Oscoliscs scope

What units would we use to describe those sounds?

Decibels

What is the crest of a wave?

the high point

What is the wavelength of a wave?

Distance between two successive points that are similar on the graph (same as period) (Top of the top)

What is the frequency of a wave?

How often the vibration occurs (How many of the waves are passing a point in a specific amount of time)

Measured in Hertz

Wavelength and frequency have what kind of relationship?

unproportional (high frequency = low wavelength)

What is the amplitude of a wave?

Height of the crest (From midpoint to the top)

What is a pendulum?

Used to understand waves

Law of pendulum - everytime it moves back and forth, it goes same distance back and forth (Like a cradle rocking)

What is pitch?

• The “tone” - High or Low

  • Low pitches have short frequencies and long wavelengths

  • High pitches have high frequencies and short wavelengths

True or False: Humans and animals have the same level of frequencies that they can hear

False - Human range of frequencies is different for animals, and age

Why is sound transfer in air, not the best?

because the sound molecules interfere with other molecules in the air

What is compression?

When air molecules are energized and bump into one another, and gets to our eardrums and compresses, and then we can hear (Energy given to something else - causes molecules to press towards something)

What is loudness? Is it relative?

the intensity (can be measured - What is measured is the amplitude)

relative - depends on the individual

What is forced vibration?

When we create a vibration, and put it on something else, we are forcing the vibration on something else

FORCES something else to vibrate due the the vibration

What is natural frequency?

The rate of waves (energy) that is minimal to require vibrations in that object

What is resonance?

When natural frequency of an object and forced vibration placed upon it are equal

What are beats?

Two different sounds that are being made, but as they interact with each other, they create a beat