Waves in Solids Can Phones- Vibrations travel along solid string better than air.
Sound in Space Sound needs a medium (Air, String and even water) We can prove this by sucking all the air out of a jar with an electric bell inside We can hear the bell ringing loudly in the jar
Sound in Space Sound needs a medium (Air, String and even water) We can prove this by sucking all the air out of a jar with an electric bell inside We suck out the air using a vacuum pump
Sound in Space Sound needs a medium (Air, String and even water) to travel in We can prove this by sucking all the air out of a jar with an electric bell inside When we have sucked out all the air from the jar we can not hear the electric bell Glass bell jar Vacuum Electric Bell
In space no one can hear you scream! Ahhhhhhhhhhhhhhhhhhh hhhhhh! Let me in!!!!!!
Thunder and Lightning When we see lightning why do we have to wait for the thunder? Light travels faster than sound. Light travels at 300000000m/s Sound travels at 340m/s Travels 1km in 0.000001s Travels 1km in 3s
Hearing Protection Our eardrums respond to vibrations by vibrating and the bones and nerves detect this and send the message to the brain. Too much vibration damages this drum and bones. (e.g. some of your ‘Music with Rocks in it’) So if the words Hip and Hop appear in the same sentence please reach for the ear protectors.
Echo A reflected sound wave If sound takes 2s to get to the cliff and return and sound travels at 340m/s. Distance = Speed x time=340x2 =680m, but how far away is the cliff face? Sound Echo D=340m
Ultrasound Ultrasound is the region of of very high frequency sound (above 20,000Hz )– it can’t be heard by humans. It can be used in pre- natal scanning. The sound is partly reflected at each layer
Other uses of ultrasound 1) Echo sounding The ultrasound is reflected from the sea floor. 2) Breaking down kidney stones Ultrasonic waves break kidney stones into much smaller pieces 3) Cleaning (including teeth) Ultrasound causes dirt to vibrate dirt off without damaging the object
The Structure of the Earth A thin crust - 10-100km thick A mantle – has the properties of a solid but it can also flow A core – made of molten nickel and iron. Outer part is liquid and inner part is solid How do we know this? These facts have all been discovered by examining seismic waves (earthquakes)
Seismic waves Earthquakes travel as waves through the Earth – we call them SEISMIC WAVES. There are two types: P waves: 1)They are longitudinal so they cause the ground to move up and down 2)They can pass through solids and liquids 3)They go faster through more dense material S waves: 1)They are transverse so they cause the ground to move from right to left 2)They ONLY pass through solids 3)They are slower than P waves 4)They go faster through more dense material
Seismic waves P waves travel through the Earth and are refracted when they pass through a medium S waves will only travel through a solid The paths of these waves are all curved because density is gradually changing These observations tell us 3 things about the Earth: 1) It has a thin crust, 2) it has a semi-fluid mantle where density increases with depth, 3) a core with a liquid outer part and a solid inner part.
1) Amplitude – this is height of the wave. 2) Wavelength ( ) – this is the distance between two corresponding points on the wave and is measured in metres: 3) Frequency – this is how many waves pass by every second and is measured in Hertz (Hz) Crest Trough
“Seeing” a wave 1) Quiet sound, low frequency (i.e. high wavelength): 2) Quiet sound, high frequency (i.e. low wavelength): 3) Loud sound, low frequency: 4) Loud sound, high frequency:
Musical Notes Music waves have a regular shape where noise is irregular Three Qualities frequency 1.Pitch - This is frequency of the wave. amplitude 2.Loudness - this is the amplitude of the wave. overtones 3.Timbre or Quality - The wave shape that is mainly due its overtones.