Download presentation
Presentation is loading. Please wait.
Published byGervase Knight Modified over 9 years ago
2
In chapter 13 we went over: Work › How work relates to force and distance Transfer and conservation of energy › Power Now we will learn: › How forces create waves › How waves transfer energy › How waves are classified
3
Wave: › The disturbance that transfers energy from one place to another Can transfer energy over distance without moving matter the entire distance. › Ocean waves travel kilometers without the water itself moving the same distance-the water simply moves up and down (disturbance) transferring its energy
4
Forces start a disturbance which sends a wave through the material: Rope waves: › If I flick the rope by applying a force upward then quickly apply the opposite force down, it sends a wave through the rope. › Both forces are required to start a wave
5
Water waves: › When an object is dropped into the water, the force applied causes waves to move through the water › D:\wave-interference_en.jar D:\wave-interference_en.jar Earthquake waves: › Sudden release of energy that has built up in the rock from a pushing and pulling (force) causes energy waves to be transferred through the ground
6
Medium: › Any substance that a wave moves through Water is the medium for ocean waves Rope is the medium for a rope wave Mechanical waves: › Waves that transfer energy through matter What is matter?
7
Think about an earthquake: › What type of energy is transferred during an earthquake (kinetic, potential, or mechanical) › The disturbance causes the ground to shake from side to side and up and down › As the energy is released, it travels in a wave but the ground itself does not travel with the wave › Faults and Earthquakes Faults and Earthquakes
8
Transverse waves: › The direction in which the wave travels is perpendicular, or at right angles, to the direction of the disturbance › “transverse” means across or crosswise › Look at the rope wave:
9
http://vimeo.com/6339850 http://vimeo.com/6339850
10
Longitudinal waves: › A wave that travels in the same direction as the disturbance Examples are: › Sound waves Molecules of air are set in motion which vibrate quickly causing more air molecules to vibrate › Slinky wave demo: If I pull the slinky back straight and release it, the coils move forward and backward.
11
When tracking and recording the height of waves in the ocean, scientists use: Mean: › The average of the recorded heights Median: › The middle value when all values are recorded from least to greatest Mode: › The value that occurs the most out of the data set
12
Measuring wave properties: › Crest: The highest point or peak of a wave › Trough: The lowest point or valley of a wave
13
Amplitude: › The distance between the middle of the crest to the middle of the trough in a transverse wave. › Indicates how much energy the wave is carrying (bigger the wave, the more energy) Wavelength: › The distance from the crest of one wave to the crest of the next wave › Can also be measured from trough to trough
14
Frequency: › The number of waves passing a fixed point in a certain amount of time › “frequent” means often Frequency and wavelength are related: › If the frequency increases, the wavelength shortens › If frequency decreases, the wavelength increases
15
http://www.classzone.com/books/ml_sci ence_share/vis_sim/wslm05_pg18_graph /wslm05_pg18_graph.html http://www.classzone.com/books/ml_sci ence_share/vis_sim/wslm05_pg18_graph /wslm05_pg18_graph.html
16
Speed = wavelength times frequency S=λf S means speed λ (Lamda) means wavelength f means frequency
17
Reflection: › The bouncing back of a wave after it strikes a barrier Refraction: › The bending of a wave as it enters a new medium at an angle other than 90 degrees Diffraction: › The spreading out of waves through an opening or around the edge of an obstacle
18
reflection and refraction reflection and refraction
20
› D:\wave-interference_en.jar D:\wave-interference_en.jar
21
Interference: › The meeting and combining of waves › They can add to or take away energy from each other Constructive interference: › The adding of two waves › Makes a larger wave out of two smaller waves › When joined perfectly, the new amplitude equals the combined amplitudes of the two original waves Waves can cancel each other out
22
Constructive interference Destructive interference
23
wave interference wave interference
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.