WoS Test 2: Unit 3 Review

Equilibrium position

The resting point of an object attached to an elastic spring.

Kinetic energy

The energy an object possesses during motion.

Potential energy

The energy stored in an object due to its position, properties, and forces acting on it.

Amplitude of displacement

The maximum displacement on a wave.

Period

Time in seconds/number of cycles.

Frequency

Number of cycles/time in seconds.

Graphs of displacement

Show how the displacement of a moving object changes with time.

What happens as the length of a pendulum string increases?

Increased period, decreased frequency.

Starting phase

The position of the start of a waveform.

Relative phase

The difference in phase angles between two signals at a given time.

Instantaneous phase

The unique single value of the phase of a signal at any given time, measured in radians.

0 radians

0 degrees

π/2 radians

90 degrees

π

180 degrees

3π/2

270 degrees

2π

360 degrees

Elasticity

A material’s ability to return to it’s original shape after a force has been applied to it.

Inertia

The inherent property of a body that makes it oppose any force that would cause a change in its motion.

Hooke’s Law of Elasticity

The force produced by an elastic object is linearly proportional to its extension (if a spring is extended, the force of elasticity works against the extension, and if the spring is compressed, the force of elasticity works against the compression).

How do elasticity and inertia effect vibration?

The resonant frequency of vibration depends on the inertia and elasticity of the vibrating system.

Resonance frequency

The frequency of free vibration.

How does mass/inertia affect the resonant frequency?

Increasing inertia decreases the resonant frequency.

How does stiffness affect the resonant frequency?

Increasing stiffness increases the resonant frequency.

How does friction effect vibrations?

Friction dampens vibrations.

Forced vibration

Motion of a vibrating system that occurs due to externally applied forces.

How do you find fundamental frequency?

Find the greatest common factor of all frequencies.

How do you find fundamental period?

Divide the fundamental frequency from 1.

Octaves

Ratios between frequencies, with one octave corresponding to a doubling of frequency.

Harmonics

Frequencies that are whole number multiples of the resonant frequency.

Amplitude spectrum

Specifies the amplitude of waves as a function.

Phase spectrum

A measure of the relative phase difference between the different waves of a waveform.

Time waveform

A graphical representation of amplitude over time.

What does the x-axis of a time waveform show?

Time (in seconds)

What does the y-axis of a time waveform show?

Amplitude

Line spectra

Consists of discrete lines with gaps between them.

Continuous spectra

Consists of continuous bands with a range of wavelengths.

Node

A point along a standing wave where the wave has minimum amplitude.

Antinode

A point along a standing wave where the wave has maximum amplitude.