1. Types of Waves Parts of the Wave Ch 17

2. In a wave pool, the waves carry energy across the pool. You can see the effects of a wave's energy when the wave lifts people in the water.

3. A. The Nature of Waves 1. What is a wave a. A wave is a disturbance that transfers energy from one place to another. b. The material through which a wave travels is called a medium. c. Solids, liquids, and gases all can act as mediums. d. A vibration is a repeating back-and-forth motion and waves start with a vibration.

4. B. Mechanical Waves 1. There are two main types of mechanical waves – transverse and longitudinal. 2. Mechanical waves require a medium. Crests

5. 1. When you shake one end of a rope up and down, the vibration causes a wave. a. The highest point of the wave is the crest. b. The lowest point of the wave is the trough. c. Rest Position is an imaginary line through the middle of the wave. d. Amplitude – height of wave e. Wavelength – measures crest to crest or trough to trought Rest position C. Transverse Wave: The particles in the wave travel up and down while the wave travels left to right.

6. Transverse Waves 2. The energy of the wave moves to the right in one direction. The bobber moves up and down in a circular motion and returns to the original position.

7. D. Compressional waves (also called longitudinal waves) 1. Particles move in the same direction that the wave is traveling in.

8. 2. Parts of a Compressional (or Longitudinal) Wave a. Compression: Wave is “bunched together” b. Rarefaction: Wave is spread far apart c. Wavelength: Distance from compression to compression or rarefaction to rarefaction A to C and B to D represent wavelengths in a compressional wave

9. D. Wave Properties 1. Frequency: the number of complete cycles in a given time. 2. A wave’s frequency equals the frequency of the vibrating source producing the wave. a. You can calculate frequency by finding the time it takes one crest or trough to travel through one point and having that time divided by one b. Frequency (Hz) = 1 / Time (sec) c. The unit of frequency is Hertz (Hz)

10. 3. Amplitude and Energy a. Greater the amplitude…greater the energy carried by the wave b. Amplitude in transverse: the greater the distance from rest position to the crest or trough is from the rest position, the greater the energy c. Amplitude in compressional: the more tightly packed the compression is, the greater the energy

11. C. Behavior of Waves 1. Types of Interference a. Occurs when two waves combine into one b. Constructive: the wave gets bigger because the crests and troughs overlap c. Destructive: the wave gets smaller because a crest and a trough overlaps

12. C. Behavior of Waves 2. Standing waves and Resonance a. A standing wave is a special type of wave that forms when waves equal in wavelength and amplitude, but traveling in opposite directions, continuously interfere with each other; 1. Node is the place at which the two waves seem to cancel, the rope does not move at the nodes b. Resonance is when an object vibrates at its natural frequency; important in music