Midterm 3 Review Vocabulary

Vocabulary flashcards covering gas laws, waves, sound, and work-energy topics for Midterm 3 review.

Ideal Gas Law

Equation (PV = nRT) that relates pressure, volume, temperature, and moles of an ideal gas.

Atomic Mass Unit (amu)

A mass unit equal to 1⁄12 the mass of a carbon-12 atom (≈1.66 × 10⁻²⁷ kg).

Molecular Mass

The sum of atomic masses of all atoms in a molecule, expressed in amu.

Mole

Amount of substance containing exactly Avogadro’s number of particles.

Avogadro’s Number

6.022 × 10²³ particles per mole.

Number of Moles (n)

Quantity of substance calculated by n = mass / molar mass.

Molar Mass

Mass of one mole of a substance; units: g mol⁻¹.

Boyle’s Law

For fixed T and n, pressure is inversely proportional to volume (PV = constant).

Charles’ Law

For fixed P and n, volume is directly proportional to absolute temperature (V ∝ T).

Kinetic Theory of Gases

Model treating gas molecules as small particles in random motion whose average kinetic energy is proportional to temperature.

Longitudinal Wave

Wave where particle displacement is parallel to the direction of propagation (e.g., sound).

Transverse Wave

Wave where particle displacement is perpendicular to the direction of propagation (e.g., waves on a string).

Amplitude

Maximum displacement of a particle from equilibrium position; units: meters.

Wavelength (λ)

Spatial period of the wave—the distance between successive identical points; units: meters.

Period (T)

Time for one complete cycle of a wave; units: seconds.

Frequency (f)

Number of cycles per second; f = 1/T; units: hertz (Hz).

Wave Speed (v)

Rate at which a wave crest travels: v = λf.

Tension (FT)

Pulling force along a stretched string or rope affecting wave speed.

Linear Mass Density (μ)

Mass per unit length of a string (kg m⁻¹).

Sound Wave

Longitudinal pressure wave that propagates through a medium by particle compression and rarefaction.

Speed of Sound

Rate at which sound travels; fastest in solids, slower in liquids, slowest in gases.

Power of a Sound Wave

Energy transported per second by a sound wave; units: watts (W).

Intensity (I)

Sound power per unit area: I = P/A; units: W m⁻².

Decibel (dB)

Logarithmic unit of sound level: β = 10 log₁₀(I/I₀).

Loudness

Perceived intensity of sound, related to decibel level and human hearing response.

Work (W)

Energy transferred by a force: W = F s cosθ; units: joules (J).

Positive Work

Work done when force component is in same direction as displacement (W > 0).

Negative Work

Work done when force component opposes displacement (W < 0).

Work–Kinetic Energy Theorem

Net work on an object equals its change in kinetic energy (W_net = ΔKE).

Kinetic Energy (KE)

Energy of motion: KE = ½ mv².

Potential Energy (PE)

Stored energy due to position or configuration within a conservative force field.

Gravitational Potential Energy (GPE)

PE associated with height in a gravitational field: GPE = m g Δh.

Spring (Elastic) Potential Energy

PE stored in a stretched/compressed spring: EPE = ½ k (Δx)².

Conservative Force

Force for which work is path-independent and converts between KE and PE (e.g., gravity, spring force).

Non-Conservative Force

Force whose work depends on path and transforms mechanical energy into other forms (e.g., friction).

Total Mechanical Energy

Sum of KE and PE of a system; constant when only conservative forces do work.

Power (P)

Rate of doing work or transferring energy: P = W/t = F v cosθ; units: watts (W).