MCAT: Physics concepts

Some physics concepts, trends, and equations

Power Equation

Power= Δt Work ​
 , measured in Joules per second (Watts) where Work is in Joules and time is in seconds

Continuity Equation and Velocity

In fluid flow, fluid velocity increases as the cross-sectional pipe area decreases (A₁V₁ ​=A₂V₂ )

Gibbs Free Energy Equation

ΔG=ΔH−TΔS, where ΔG is free energy change, ΔH is enthalpy, T is absolute temperature in Kelvin, and ΔS is entropy

Specific Heat Capacity Formula

q=mcΔT (or c= mΔT q ), where C or c is specific heat, Q is heat energy, m is mass, and ΔT is temperature change

Closed Pipe Harmonics

Pipes closed at one end only produce odd integer harmonics (n=1,3,5…) with resonant frequencies that are odd multiples of the fundamental frequency

Open Pipe and Fixed String Harmonics

Pipes open at both ends and strings fixed at both ends allow all integer harmonics (n=1,2,3…), producing both even and odd multiples of the fundamental frequency

Fundamental Frequency

The lowest possible resonant frequency (n=1) in a standing wave system. Fractional multiples (like f/2) cannot exist as resonant states

Total Internal Reflection Conditions

Occurs when light travels from a medium of higher index of refraction to one of lower index (n1>n 2 ​) and the angle of incidence exceeds the critical angle (θ₁ >θ_c ​)

Elastic Potential Energy Equation

PE_el = 1/2kx², where k is the spring constant and x is displacement from equilibrium

Decibel Intensity Ratio Calculation

Subtract the initial decibel value from the final decibel value to find Δβ, divide Δβ by 10 to find exponent x, then calculate 10 x   to find the ratio of sound intensities

Hydrostatic Pressure Formula

P=ρgh, where P is pressure, ρ is fluid density, g is acceleration due to gravity, and h is depth beneath the fluid surface

Torque Equation

τ=Frsin(θ), where F is applied force, r is lever arm distance from pivot, and θ is the angle between force and lever arm

Photon Energy Equation

Energy equals Planck's constant times frequency (E = hf), meaning photon energy is directly proportional to frequency

Wave Frequency Invariance

Wave frequency is determined entirely by the source and remains unchanged when passing through different media, whereas wave speed, amplitude, and wavelength change

Wave Velocity Frequency Wavelength Equation

Wavelength equals wave speed divided by frequency, where converting megahertz to hertz yields wavelength in meters

Uniform Electric Field Characteristics

A uniform electric field exerts a constant force on a charge everywhere within the field, represented by straight and equally spaced field lines

Resistivity versus Conductivity

Resistivity measures a material's intrinsic resistance to electrical current while conductivity measures its ability to conduct current, making them reciprocal inverses of each other

Continuity Equation for Fluid Flow

Volume flow rate equals cross-sectional area times fluid velocity (A1V1 = A2V2), demonstrating that fluid speed increases as pipe cross-sectional area decreases

Length Unit Conversion for Nanometers

One meter equals ten to the ninth power nanometers, meaning to convert nanometers to meters you multiply by ten to the negative ninth power

Hydrostatic Pressure Equation

Hydrostatic pressure equals ambient pressure plus the product of fluid density, gravitational acceleration, and depth (P = P0 + rho g z)

Work Equation by Constant Force

Work equals force times displacement times the cosine of the angle between force and displacement vectors (W = F d cos theta)

Work Energy Theorem

Net work performed on an object equals its change in kinetic energy (Wnet = delta KE)

Continuity Equation for Volumetric Flow Rate

Flow rate Q remains constant in an incompressible fluid and equals cross sectional area times fluid velocity (Q = A v)

Poiseuille Law for Laminar Flow Rate

Flow rate is directly proportional to pressure drop and radius to the fourth power, and inversely proportional to fluid viscosity and pipe length

Ohm Law for Electrical Circuits

Voltage drop across a resistor equals current times resistance (V = I R)

Electric Power Equations

Electrical power dissipated or delivered equals current times voltage, which can also be written as current squared times resistance, or voltage squared divided by resistance

Coulomb Law for Electrostatic Force

The magnitude of electrostatic force between two point charges equals Coulomb constant times the product of absolute charges divided by square of distance (F = k q1 q2 / r^2)

Electric Field Magnitude Equation

Electric field magnitude equals force per unit charge, or Coulomb constant times source charge divided by square of distance (E = k Q / r^2)

Capacitance Fundamental Equation

Capacitance equals charge stored per unit voltage across the parallel plates (C = Q / V)

Capacitance of Parallel Plate Capacitor

Capacitance equals vacuum permittivity times plate area divided by separation distance (C = epsilon0 A / d)

Potential Energy Stored in a Capacitor

Stored electrical potential energy equals one half times capacitance times voltage squared (U = 1/2 C V^2)

Equivalent Resistance in Series versus Parallel

Equivalent resistance sums directly for resistors in series, whereas reciprocal of equivalent resistance equals sum of reciprocal resistances in parallel

Equivalent Capacitance in Series versus Parallel

Equivalent capacitance sums directly for capacitors in parallel, whereas reciprocal of equivalent capacitance equals sum of reciprocal capacitances in series

Torque Equation

Torque magnitude equals force times lever arm distance times the sine of the angle between force vector and lever arm (tau = r F sin theta)

Linear Elasticity Hooke Law

Restoring force of an ideal spring equals negative spring constant times displacement from equilibrium (F = -k x)

Elastic Potential Energy Equation

Potential energy stored in a stretched or compressed spring equals one half times spring constant times displacement squared (U = 1/2 k x^2)

Snell Law of Refraction

Index of refraction of first medium times sine of incident angle equals index of refraction of second medium times sine of refracted angle (n1 sin theta1 = n2 sin theta2)

Thin Lens Equation

Reciprocal of focal length equals reciprocal of object distance plus reciprocal of image distance (1 / f = 1 / do + 1 / di)

Magnification Equation

Magnification equals negative image distance divided by object distance, which also equals image height divided by object height (M = -di / do)

Force Unit Newton Breakdown

The Newton is the SI unit of force, equivalent to one kilogram meter per second squared (N = kg m / s^2)

Energy Unit Joule Breakdown

The Joule is the SI unit of energy and work, equivalent to one Newton meter or one kilogram meter squared per second squared (J = N m = kg m^2 / s^2)

Power Unit Watt Breakdown

The Watt is the SI unit of power, equivalent to one Joule per second or one kilogram meter squared per second cubed (W = J / s = kg m^2 / s^3)

Capacitance Unit Farad Breakdown

The Farad is the SI unit of electrical capacitance, equivalent to one Coulomb per Volt (F = C / V)

Pressure Unit Pascal Breakdown

The Pascal is the SI unit of pressure, equivalent to one Newton per square meter or one kilogram per meter second squared (Pa = N / m^2)

Charge Unit Coulomb Breakdown

The Coulomb is the SI unit of electric charge, equivalent to one Ampere second (C = A s)

Voltage Unit Volt Breakdown

The Volt is the SI unit of electric potential, equivalent to one Joule per Coulomb (V = J / C)

Resistance Unit Ohm Breakdown

The Ohm is the SI unit of electrical resistance, equivalent to one Volt per Ampere (Omega = V / A)

Frequency Unit Hertz Breakdown

The Hertz is the SI unit of frequency, equivalent to one cycle or event per second (Hz = 1 / s)

Magnetic Field Unit Tesla Breakdown

The Tesla is the SI unit of magnetic field strength, equivalent to one Newton per Ampere meter or one Volt second per square meter (T = N / A m)

Torque Unit Newton Meter Breakdown

Torque is measured in Newton meters, representing rotational force applied at a perpendicular distance from a pivot point

Viscosity Unit Pascal Second Breakdown

Dynamic viscosity is measured in Pascal seconds, equivalent to one Newton second per square meter or one kilogram per meter second

SI Metric Prefix Giga Symbol and Factor

Symbol G represents Giga, corresponding to ten to the ninth power (10^9)

SI Metric Prefix Mega Symbol and Factor

Symbol M represents Mega, corresponding to ten to the sixth power (10^6)

SI Metric Prefix Kilo Symbol and Factor

Symbol k represents Kilo, corresponding to ten to the third power (10^3)

SI Metric Prefix Centi Symbol and Factor

Symbol c represents Centi, corresponding to ten to the negative second power (10^-2)

SI Metric Prefix Milli Symbol and Factor

Symbol m represents Milli, corresponding to ten to the negative third power (10^-3)

SI Metric Prefix Micro Symbol and Factor

Symbol mu represents Micro, corresponding to ten to the negative sixth power (10^-6)

SI Metric Prefix Nano Symbol and Factor

Symbol n represents Nano, corresponding to ten to the negative ninth power (10^-9)

Photon Energy and Stokes Shift

Photon energy equals Planck constant times frequency or Planck constant times speed of light divided by wavelength with energy lost as heat between absorbed and emitted light accounting for the Stokes shift

Wavelength and Energy Relationship

Wavelength and energy are inversely proportional so longer wavelengths correspond to lower photon energy closer to the ground state

Venturi Effect

Decreasing the cross sectional area of a pipe increases fluid velocity which causes a simultaneous drop in static pressure

Systolic Blood Pressure

The upper number in a blood pressure reading representing peak arterial pressure during ventricular contraction

Diastolic Blood Pressure

The lower number in a blood pressure reading representing minimum arterial pressure during ventricular relaxation

Molar Volume of Ideal Gas

One mole of an ideal gas occupies twenty two point four liters at standard temperature and pressure

Gravitational Power Equation

Power equals mass times gravitational acceleration times height divided by time interval with units in watts

Elastic Work Equation

Work done by an elastic force or stretching band equals one half times the spring constant times displacement squared

Decibel Ratio Calculation

To find the intensity ratio divide the decibel difference by ten and raise ten to the power of that resulting value

Diverging Lens and Convex Mirror Images

Diverging lenses and convex mirrors always produce virtual upright and reduced images

Converging Lens Image Properties

Converging lenses produce real inverted images when the object is beyond the focal length and virtual upright enlarged images when the object is within the focal length

Lens Equation Variables and Signs

Image distance i is positive for real images and negative for virtual images while magnification m equals negative i over o where negative means inverted and magnitude less than one means reduced

Battery Powered Resistive Circuit Energy

Energy converts sequentially from chemical energy in the battery to electrical energy in the circuit to thermal energy dissipated as heat across the resistor