Physical Science Waves

Mechanical Wave Mechanical Wave: Disturbance in matter that carries energy from one place to another. –Created when a source of energy causes a vibration to travel through a medium WAVES CARRY ENERGY! Vibration: Repeating back and forth motion Medium: Material. Solid, Liquid or Gas

Mechanical Wave Three types of Mechanical Waves Transverse Wave –Medium vibrates at right angles to the direction of travel –Has a Crest and Trough –Examples: Rope, tablecloth

Transverse Waves Figure 2

Mechanical Wave Longitudinal Wave –Medium vibrates parallel to the direction of travel –Has compression and rarefaction –Examples: Slinky, sound waves

Longitudinal Waves Figure 3

Mechanical Wave Surface Wave –Wave Travels along the surface separating two media –Motion both at right angles and parallel to the direction of the wave –Example: Ocean wave

Surface Waves Figure 4

Properties of Mechanical Waves Period: Time required for one cycle. One complete motion that returns to the starting point. –The longer the period, the more time it takes to complete a cycle Periodic Motion: Motion that repeats itself.

Properties of Mechanical Waves Frequency: Number of cycles in a given time. –Unit: Cycles per second = Hertz –A wave’s frequency equals the frequency of the vibrating source producing it –If the period is decreased, the frequency increases

Properties of Mechanical Waves Wavelength: Distance between a point on a wave to the same point on the next cycle –If you increase the frequency of a wave, you decrease its wavelength Wave Speed: How fast one cycle of a wave travels a certain distance –Wave Speed = Wavelength X Frequency

Properties of Mechanical Waves Amplitude: Maximum displacement of a medium from its rest position. –Maximum height of the wave crest –The GREATER the amplitude, the GREATER the energy of the wave.

Properties of Mechanical Waves - Amplitude

Behavior of Waves Reflection: Occurs when a wave bounces off of a medium that it cannot pass through. –Reflection doesn’t change the wave’s speed or frequency. –Reflection can flip the wave upside down

Behavior of Waves Refraction: Bending of a wave as it enters a new medium –Occurs when a wave enters a medium at an angle –One part of the wave moves slower than the other –Example: Waves on a beach Diffraction: Bending of a wave as it moves around an obstacle.

Behavior of Waves Interference: Two or more waves overlapping and combining –Constructive Interference: Two or more waves combine and form a wave that’s bigger –Destructive Intereference: Two or more waves combine and form a wave that’s smaller

Behavior of Waves - Interference

Behavior of Waves Standing Wave: A wave that appears to stay in one place.