bellwork …solve the riddle

Bellwork…solve the riddleA pendulum has it, water rippling on a pond shows

it, “mechanics” can explain it, a truck uses it, an acrobat on the trapeze plays with it, our brains interpret it, a grandfather clock depends on it and a spider feels it.

What is it?

• P.S. If you missed your test yesterday, come see me to set up a time to take it. You may also plan to come in 8th period tomorrow.

• P.P.S We will probably go over the test Friday• P.P.P.S. The answer is not waves

Wave Warm up Wednesday!

I. Waves are produced by oscillating particles.A. Oscillation - move or swing back and forth around a

central pointB. Periodic motion – repeated motion

Ex. Trapeze, swing, wrecking ball, grandfather clock or metronome.C. Simple harmonic motion – vibration about an equilibrium position in which a restoring force is proportional to the displacement from the equilibrium.D. Damping – the tendency of a vibrating object to dissipate its energy over time

II. Waves transfer energy from one location to another without transferring matter.

III. All waves have properties in common, such as wavelength, frequency, and energy transmission.

A. Amplitude – greatest distance from equilibrium point

B. Cycle – one complete ‘to and fro’ motionC. Period – the time required for one

complete cycle (T)D. Frequency – number of complete cycles

per second.

IV. Mechanical waves travel at different speeds in different media and undergo reflection and refraction (bending) at boundaries.

A. Medium/Media – a physical environment through which a disturbance can travel (Ex…)

B. Mechanical wave – a wave that requires a medium through which to travel

V. Waves interact with each other and produce new wave patterns at boundaries. One example would be diffraction.

VI. The properties of waves are used in devices for medical, industrial, scientific, or social purposes.

Shock absorbers

Closure

• Using the example of a bobblehead, explain how amplitude, frequency, and damping relate to its motion

Bellwork

• Draw a wave (like the one below) and label all the parts that you know/remember.

• Wavelength – where do you measure from? • The shortest distance between equivalent points on

a continuous wave.• = lambda = wavelength

Wave types and measurements

I. Wave typesA. pulse wave –single traveling pulseB. periodic wave – involves _____ motionC. Sine waves

1. describe particles vibrating with simple harmonic motion

2. special case of a periodic wave3. called a sine wave because y= sin x

• D. Standing wave

E. transverse waveex. Electromagnetic waves

F. longitudinal wave1. Sound waves2. compression3. rarefaction

II. Wave measurementsA. amplitudegreater the amplitude = more energy B. wavelengthC. Period, Frequency and Wave speed1. v = f • λ 2. Speed of a mechanical wave is constant for

any given medium3. Speed only changes when the wave moves

from one medium to another or certain properties of the medium are varied (such as temperature)

4. unit for frequency = Hertz (Hz)

Olive Udadi accompanies her father to the park for an afternoon of fun. While there, she hops on the swing and begins a motion characterized by a complete back-and-forth cycle every 2 seconds. The frequency of swing is _________.

A piano string tuned to middle C vibrates with a frequency of 262 Hz. Assuming the speed of sound in air is 343 m/s, find the wavelength of the sound waves produced by the string.

• A tuning fork produces a sound with a frequency of 256Hz and a wavelength in air of 1.35m– A. what value does this give for the speed of

sound in air?– B. What would be the wavelength of this same

sound in water in which sound travels at 1500m/s