Waves By: S

Unit 5 Mechanical waves are disturbances in matter which need a medium to travel through. These waves also carry energy from place to place. For example, if you are laying on a boogie board in the ocean and a wave (which has the energy) comes along, both you and the boogie board will go up. When you are at the top of the wave you have potential energy, but when you start to move the potential energy gets transferred into kinetic energy. Define mechanical waves and relate the waves to energy.

Unit 5 Types of WavesHow the Waves are Produced transverse waves These waves are produced when a medium (what the wave travels through) is caused to vibrate at right angles to the direction that the waves are traveling. longitudinal waves These waves are produced when a medium (what the wave is traveling through) vibrates in a parallel motion to the direction the waves are traveling. surface waves These waves are produced along a surface separating two or differing media. Describe transverse, longitudinal, and surface waves. Discuss how they are produced.

Unit 5 Types of WavesExamples of Waves transverse waves shaking a blanket or a sheet up and down making sure that if you start from the crest or trough you end in the crest or trough light waves longitudinal waves sound waves hitting a bell a crystal wine glass a spring door stop Identify examples of transverse and longitudinal waves.

Unit 5 Types of Mechanical WavesThe Motion of the Medium as Each Wave Passes Through it transverse wavesAs a transverse wave passes through, the medium will vibrate at a right angle to the direction that the wave is traveling. longitudinal waves As a longitudinal wave passes through, the medium will vibrate parallel to the direction that the wave is traveling. The motion of this wave also travels in compressions (where particles are close together) and rarefactions (where the particles are spread out). surface wavesAs a surface wave passes through, this wave travels along a surface separating two or differing media. Analyze the motion of a medium as each kind of mechanical wave passes through it.

Unit 5-2 Frequency – The number of cycles completed in a given amount of time (usually one second). period – The time needed for one complete cycle that returns to its starting point. wavelength – The distance between two points, a point on one wave and the same point on the cycle of the next wave. wave speed – distance/time Define frequency, period, wavelength, and wave speed. Describe these properties for different kinds of waves. Describing These Properties For Waves To find the wave speed, you have to find the distance of the wave and divide it by the time it takes for the wave to reach that distance. The top bars on this wave represent the crest and the bottom bars represent the trough. So from one crest or trough bar to the other is the period because it is a complete cycle that returns to its starting point. From one point on a wave to the to that same point on the next cycle of the wave is the wavelength. Example A would have a higher frequency than example B. This is because A has more cycles per one second than B does, which means that the waves are moving faster in example A.

Unit 5-2 To measure amplitude you have to find the height of a wave from its resting position. The greater amount of energy that the wave has, the greater that the wave’s amplitude will be. Describe how to measure amplitude and relate amplitude to the energy of the wave

Unit 5-3 Terms That Deal With WavesHow They Affect Waves reflection It may cause the wave to be flipped upside down. refractionAs a wave enters a new medium at an angle, refraction causes the wave to bend. diffractionAs a wave moves around or passes through a narrow object or obstacle, diffraction causes the wave to bend. interferenceInterference is when two or maybe more waves overlap and then combine together. Describe how reflection, refraction, diffraction, and interference affect waves.

Unit 5-3 A rule that explains refraction of a wave as it passes from one medium to another is that when a wave is going into a new medium at an angle, refraction takes place because one side of the wave moves more slowly than the other side. State a rule that explains refraction of a wave as it passes from one medium to another.

Unit 5-3 All the type of medium that the wave is traveling through the type of wave the angle that the wave moves from one medium to another Refraction Only how much the wave bends the speed of the waves Diffraction Only the size of the opening or obstacle the size of the wavelength Interference Only how much the waves overlap and combine together Identify factors that affect the amount of refraction, diffraction, or interference.

Unit 5-3 The difference between constructive and destructive interference is that constructive interference is when two waves combine to produce a wave with a greater amplitude and destructive interference is when two waves combine and produce a wave with smaller displacement. constructive interference – When two waves combine, the crests of those waves will combine to produce a higher crest and the two troughs will combine to produce a lower trough. destructive interference – When two waves combine, the crest of one wave will meet the trough of the other wave and result to have a crest lower than the crest of both of the waves (one or two). At certain frequencies, as a result of interference, two waves traveling in opposite directions can produce a standing wave. Distinguish between constructive and destructive interference and explain how standing waves form.

Unit 5-4 Sound Wave Properties speed frequency pitch intensity loudness Sound is produced when a medium is disturbed and the molecules in the medium are set into motion. To reproduce sound, you convert the electronic signals into sound waves. Describe the properties of sound waves and explain how sound is produced and reproduced.

Unit 5-4 In music, by changing the frequency of standing waves, the pitch that comes out will vary. So in a wind instrument the notes can either be opened or closed and depending on the length of the column of air, standing waves (sound waves) are produced. In string instruments, you can either make the strings longer or shorter using your fingers to get standing waves (sound waves). An ultrasound is sound at frequencies higher than almost every one hears. In sonar (which ultrasound is used in), waves are sent out and the distance to that object is calculated by using the speed of sound in water. When the sound waves reach an object, they bounce off and send back an echo that says where something is located. Describe how sound waves behave in ultrasound and music

Unit 5-4 Relative motion determines the frequency of sound an observer hears because for instance in the Doppler Effect, as any source of sound approaches, the observer would hear a higher frequency. When the source of sound moves away, the observer would hear a lower frequency. Explain how relative motion determines the frequency of sound an observer hears.

Unit 5-4 outer ear – gathers while focusing sounds to the middle ear middle ear – receives and amplifies vibrations inner ear – senses vibrations while using nerve endings and sends signals to the brain Analyze the functions of the main regions of the human ear.