 LESSON
Waves & Vibrations - Basics
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Waves & Vibrations - Basics

Body text Wave Vocab

• Periodic motion - any motion that repeats itself over and over

• Wave - a disturbance that carries energy as it moves (or propagates).

• Oscillation - repeated back and forth motion at a regular speed

• Period - the time required to complete one wave

• Frequency - the number of oscillations per second

• Hertz - the unit for frequency

• Amplitude - the maximum displacement from equilibrium

Q. What is the length between one point of a wave to the same point on the next wave called?
Wavelength
Trough
Amplitude
Crest
Q.

The distance from the equilibrium position to the crest or trough is called the what? Also known as the height of a wave.

Trough

Wavelength

Amplitude

Crest

Q.

The distance from the equilibrium position to the crest or trough is called the what? Also known as the height of a wave.

Trough

Wavelength

Amplitude

Crest

Vocab (continued)

• Crest - the highest point in a wave

• Trough - the lowest point in a wave

• Compression - points on a wave that a pushed close together

• Rarefaction - points on a wave that spread apart

• Transverse Wave- wave in which the particles oscillate at right angles to the direction the wave travels

• Longitudinal Wave- wave in which the particles oscillate parallel to the direction of propagation

• Phase - the position of a point in time (an instant) on a waveform cycle

Vocab (continued)

• Simple harmonic motion - periodic motion that occurs when the restoring force an object is proportional to the displacement from equilibrium

• Hooke’s Law - the law that states that the force exerted by an ideal spring is spring proportional to the distance by which it is stretched or compressed.

• Restoring force - the force that acts to bring an object back to equilibrium

• Simple Pendulum - an object (or mass) suspended by a light rope or rod

• Wave Speed - the rate at which a wave travels (m/s)

Q.

Define restoring force

a force that acts to bring an object back to equilibrium

the position of a point in time (an instant) on a waveform cycle

the frequency at which an object oscillates by itself

the phenomenon where an object is driven (forced to vibrate) at its natural frequency

Q.

Define Hooke's Law

periodic motion that occurs when the force pushing or pulling an object toward equilibrium is proportional to the displacement from equilibrium

repeated back and forth motion at a regular speed

the force exerted by an ideal spring is spring proportional to the distance by which it is stretched or compressed.

the phenomenon where an object is driven (forced to vibrate) at its natural frequency

Vocab Continued

• Natural Frequency - the frequency at which an object vibrates normally (naturally)

• Resonance - the phenomenon where an object is driven (forced to vibrate) at its natural frequency

• Harmonic - a multiple of an object's natural frequency

• Medium- the matter through which a wave travels

• Mechanical Wave- waves that travel through matter

Q.

Define Resonance

periodic motion that occurs when the force pushing or pulling an object toward equilibrium is proportional to the displacement from equilibrium

repeated back and forth motion at a regular speed

the force exerted by an ideal spring is spring proportional to the distance by which it is stretched or compressed.

the phenomenon where an object is driven (forced to vibrate) at its natural frequency

Q. Waves transfer ________, but they do not transfer _________.
Matter, Energy
Energy, Matter

Waves & Oscillations

• Waves carry energy as they travel, not matter

• EX - the sun transmits light waves to Earth but none of the sun travels with it.

• Oscillations occur when an object is moving back and forth.

• Oscillations have wave-like motion

• Oscillations and waves have a frequncy, period, wave speed, etc. Waves

• Period --> T = t / n or T = 1 / f

• Frequency --> f = n / t or f = 1 / T

• Wave Speed -->

$v\ =\ \lambda f\ or\ v\ =\frac{\lambda}{T}\$

• Wavelength -->  $\lambda\ =\ vT\ or\ \lambda=\frac{v}{f}$ Q.  A wave has frequency of 5 Hz and a speed of 25 m/s. What is the wavelength of the wave?
25 m
125 m
5 m
25 m/s
Q. A tennis coach paces back and forth along the sideline 10 times in 2 minutes. The frequency of her pacing is
5 Hz
5 s
0.08 Hz
0.08 s
Q.

A wave has frequency of 50 Hz and a wavelength of 10 m. What is the speed of the wave?

500 m/s

50 m/s

5 m/s

0.5 m/s Q.

If this wave chain represents 1 second, What is the frequency of the waves?

1 Hz

9 Hz

3 Hz

6 Hz

Q. One end of the rope is vibrated to produce a wave with a wavelength of .25 m.  The Frequency of the wave is 3.0 Hz.  What is the speed of the wave?
3.00 m/s
2.50 m/s
.75 m/s
1.25 m/s Q.

what type of wave is it? 