Physical Science Chapter 10 (New Book) .ppt

7/26/2019 Physical Science Chapter 10 (New Book) .ppt

1/74

Physical ScienceCh. 10: Waves


2/74

A wave is a rhythmic disturbance which carriesenergy through space or matter.

Many waves, but not all, require a medium to movebetween points, these are called mechanicalwaves.

A medium is a material through which a wavetransfers energy.


3/74

Which of the following would bemechanical waves?

Light ound

!ltraviolet "!.#.$ waves


4/74

%ypes of Waves

&ased on the way they move, there

are ' different types of waves(

). %ransverse Waves

'. *ompressional Waves


5/74

%ransverse Waves

+n a transverse wave, the waves mediummove perpendicular to the direction of the

wave. -. ocean waves, light waves

/or eample, as the wave moves left to right,the medium moves up and down.


6/74

ay youre waters0iingdown at the la0e andyou wipe out. As youfloat in the water and awave goes by, whatdoes your body do asthe wave passes?


7/74


8/74


9/74


10/74

Parts of a Transverse Wave

%here are 1 main parts to a transverse wave(

*rest2 the highest point on a transverse

wave

%rough2 the lowest point on a transverse

wave


11/74

Amplitude2 the distance from either the

crest or trough to the resting point of thewave


12/74

Wavelength2 distance from crest to crest

or trough to trough on a wave


13/74


14/74

Wave /requency

/requency is a property of a wave, not apart of one.

/requency is the number of waves whichpass a given point in ) second.

3ert4 "34$ is the + unit for frequency.

) 34 5 ) wave passing a given point in

) second


15/74

o if you6re sitting on a boatdoc0, and ) waves washes

up against the doc0 everysecond, then the wavefrequency is ) 34.

What if ' waves hit persecond?

What if ) waves washes pastevery ' seconds?


16/74

When you tune in to a radio station, thenumbers on the dial represent the frequencythat a particular station is sending their signal

out at./M 7 M34 "megahert4$, 89.8 5 89,8::,::: 34

AM 7 ;34 "0ilohert4$,


17/74

Which band, AM or /M, usually has better

sound quality? Why do you thin0 this is so?


18/74

%he period of a wave is the amount of time itta0es one wavelength to pass a stationary

point. %he wave below has a period of about' s.


19/74

Compressional Waves

A compressional wave vibrates in thedirection that the wave is travelling. Thesewaves are also known as longitudinal waves.

Examples slink!" sound waves


20/74

%he ' main parts of a compressional wave are(A. *ompression2 area of higher density

within the wave&. =arefaction2 area of lower density

within the wave pg. '8


21/74


22/74

ound Wavesound Waves

ound waves are a type of compressional

wave which require a medium to travel.

ound waves travel at about >: mi@hr.

%his speed is effected slightly by the type

of medium, temperature of medium, and

elevation.


23/74

When an obect such as a et travels at aspeed greater than >: mi@hr it is said tobe supersonic.

What happens when an obect travels atsupersonic speeds?


24/74


25/74

%he %hrust* "supersonic car$ bro0e thesound barrier on land, going >.


26/74

%he photo below shows the shoc0 waveproduced when the car bro0e the soundbarrier.


27/74

A shoc0 wave is a rapid change in air pressurecaused by a strong disturbance. %he shoc0 wavemoves outward from the disturbance.

Large eplosions and sonic booms can producestrong shoc0 waves.


28/74

%hin0 of a roc0 being thrown into a pondand producing outward ripples. A strong

disturbance can produce the same typeof ripples, only in the air.


29/74

A boat moving though water can producewaves which are more bunched up in front of

the boat in the direction that it is moving. othere are more waves per second"frequency$ out in front of the boat.


30/74

Let6s say that the boat travels fast enoughfor the waves being produced to start to

overlap each other, so that a stationarypoint "$ is hit by more than ) wave at atime.


31/74

%his would cause that point to eperience

much more wave energy all at once.


32/74

%his is fairly easy for the boat to accomplishsince all it would have to do is move faster thanthe waves, which travel relatively slowly.3owever, the same thing can happen in the airif the obect "a et$ can travel faster than thewaves in the air "sound waves$.


33/74

When the tremendous amount of energyrequired for this to occur produces waves,

and these waves start overlapping andstri0ing a point several at a time, then a sonicboom is eperienced.

Cust li0e the boat produces continual waves


34/74

Cust li0e the boat produces continual waves,so does the et. o as long as it stays above>: mi@hr, a continual sonic boom will be

produced following along slightly behind theet.


35/74


36/74

+f you are on the ground as the et goesover, you will here only a single boomthough, as the shoc0 wave moves pastyou following the et.


37/74


38/74

3ow far away can a sonic boom be felt orheard?

What happens as the et drops bac0 below>: mi@hr?


39/74

Wave speed is the rate at which a wave is

traveling, and is measured in m@s.

%he formula for wave speed is(

frequency "34$ wavelength "m$


40/74

+f a sound wave "DD m@s$ has a frequency

of 34, what is its wavelength?


41/74

#elocity 5 /requency Wavelength

so

Wavelength 5 #elocity @ /requency

5 DD m@s @ 34

5 5 m

= fl i d = f i


42/74

=eflection and =efraction

=eflection is where a wave stri0es an obect and

bounces off. When a wave stri0es a flat reflective surface it will

reflect bac0 at the same angle that it struc0 the

surface at. %his is calledEEE


43/74

%he Law of =eflection

%he law of reflection states that the angleof incidence is equal to the angle of

reflection on a flat reflective surface.


44/74

-amples of the Law of

=eflection(


45/74

3ow is the Law of =eflection used in lasersecurity systems?


46/74

+n addition to reflection a wave caneperience refraction.

=efraction is the bending of a wave as itenters a different medium, due to achange in speed.


47/74

&ecause of light refraction, a person bowfishing would not aim directly at the fish.

Where should they aim? 3mmmmEEE..


48/74

Fiffraction Fiffraction is the bending of a wave, around a

barrier.

-.( Light in the storage room partially illuminating the

classroom.


49/74

ometimes ' or more waves may come incontact with each other and overlap to form a

new wave. %his is called interference

As these waves overlap, they can eithermultiply and enhance each other, or canceleach other out.


50/74

*onstructive interference occurs when thecrests and troughs coincide and produce a

larger amplitude "greater overall combined energy$


51/74


52/74


53/74

-amples of constructive interference(

7 ' people trampolining at the same time

7 ' or more people singing together "in sync$


54/74

Festructive interference occurs when thecrests of one wave coincide with the troughs

of another, creating a smaller amplitude.


55/74

- l


56/74

-amples(

2 ecessive echoing in a stadium or arena,

which distorts the G.A. system2 ' or more people singing together "out of

sync$

i d i h H i l A h ill f


57/74

ingers doing the Hational Anthem will often

wear earplugs because the strong echo

coming bac0 through the stadium caninterrupt their timing of the song.


58/74

Many locations, such as auditoriums andmodern stadiums are specifically designed

to produce constructive interference.


59/74

Waves created through and along thecrust of the earth by shifting or brea0ing

tectonic plates are called seismic waves.

%hese waves are comprised of


60/74

pboth transverse andcompressional waves, and can

create very damagingearthqua0es.


61/74

%he an Andreas /aultline in *alifornia and the

Hew Madrid /ault in -Missouri are ' locationswhere plates come

together, and aretherefore more li0ely toslide or brea0.


62/74


63/74

!nderwater earthqua0es can oftenproduce tsunamis, giant ocean waves.


64/74


65/74


66/74


67/74


68/74

When Foug was driving

from ;ansas *ity to

Fenver, he crossed overfrom the central time 4one

to the mountain time

4one. When he arrivedhe went to change the

time on his cell phone,

but found that it had

already changed. 3ow

did that happen?


69/74

As *arl was driving

through the B4ar0s, hefound that he could not

tune into a radio station

and maintain a signal,even for stations nearby.

Why was this?

%he outh American


70/74

%he outh Americanarcher fish shoots astream of water

which 0noc0sunsuspecting preydown into the waterwhere they areeaten. Would thefish in the pictureneed to aim higher

or lower than whereit perceives the bugto be?


71/74

A : caliber sniper rifle fires a proectile at


72/74

A .: caliber sniper rifle fires a proectile at),::' m@s. +f the rifle is fired at a target andthe bullet ta0es ' seconds to reach thetarget, how long after the bullet stri0es will itta0e before the crac0 of the gun is heard?"speed of sound 5 DD1 m@s$


73/74

&ecause sound travels at >: mi@hr, you can

calculate that it will travel about ) mile in

seconds.

) hr. 5 D,:@D,


74/74

p p gthe sound barrier, producing a sonic boom.+f you hear the boom ) minute after the et

passed by, how high was the et flying?

Physical Science Chapter 10 (New Book) .ppt

Documents