MCAT Physics Review

505 terms by GKAdams2012 

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Combination of terms from other sets

ac current

(alternating current) the movement of electric charge periodically reverses direction

alpha decay

an alpha particle is lost (type of radioactive decay)

alpha particle

a helium nucleus (2 protons, 2 neutrons)

angular magnification

magnification expressed as the ratio of the angle α′ subtended at the eye by the image to the angle α subtended at the eye by the object

antinode

point on two waves with the same wavelength traveling in opposite direction where the movement is maximized; highest amplitude

atmospheric pressure

101,000 Pa

beats

occur when two waves with slightly different frequencies are superimposed

beta decay

expulsion of an electron (type of radioactive decay)

bulk modulus

modulus for compression and expansion

buoyant force

(Fb) an upward force acting on a submerged object, and is equal to the weight of the fluid displaced by the submerged object

capacitance

the ability to sore charge per unit voltage; a high capacitance means it can store a lot of charge at low voltage

chromatic dispersion

the dispersion of light; the phenomenon in which the phase velocity of a wave depends on its frequency

completely inelastic collisions

occur when objects stick together; lose some energy to internal energy

concave mirror

a mirror with a curved reflective surface that is bulging inward

conservative force

energy change is the same regardless of the path taken by the system; total work done is zero if the system moves from A to B and back to A

constructive interference

occurs when the sum of the displacements of waves results in a greater displacement

converging lens

a lens that acts like a convex mirror; larger at the middle

convex mirror

a mirror with a curved reflective surface that is bulging outward

critical angle

the angle of incidence above which total internal reflection occurs; angle at which light is reflected

dc current

(direct current) the unidirectional flow of electric charge

density

(p) the 'heaviness' of a fluid; mass/volume

density of water

1000 kg/m^3 aka 1 gm/cm^3

destructive interference

occurs when the sum of the displacements of waves results in a smaller displacement

dielectric constant, K

refers to the substance between the plates of a capacitor; the ratio of the capacitance of a capacitor in which a particular insulating material is the dielectric, to its capacitance in which a vacuum is the dielectric

diffraction

when a wave disperses as it goes through a small hole

diverging lens

a lens that acts like a concave mirror; thin in the middle

elastic collisions

mechanical energy is conserved which means no energy is dissipated to internal energy

electric dipole

created by two opposite charges with equal magnitude

electron capture

capture of an electron along with the merging of that electron with a proton to create a neutron; a proton is destroyed and a neutron is created (type of radioactive decay)

EMF

(electromotive force) that which tends to cause current to flow; the voltage of electricity in a circuit

equipotential surfaces

points in an electric field that have the same voltage

first harmonic

(aka fundamental wavelength) - the longest wavelength in a harmonic series

fission

the splitting of an single nucleus to form two lighter nuclei

fluid

a liquid or a gas

fluid pressure

pressure at some point within a fluid; results from the impulse of molecular collisions

focal length

a measure of how strongly the system converges (focuses) or diverges (defocuses) light

focal point

point at which initially collimated rays of light meet after passing through a convex lens, or reflecting from a concave mirror

frequency

the number of wavelengths that pass a fixed point in one second; measured in hertz (Hz), or cycles per second (1/s)

fusion

the combing of two nuclei to form a single heavier nucleus

gamma ray emission

when a gamma ray is given off; often accompanies other types of radioactive decay and does not change the identity of an element

harmonic series

the list of wavelengths from largest to smallest of the possible standing waves for a given situation; numbered from longest to shortest wavelength

heat

transfer of energy by natural flow from warmer body to cooler body

hydraulic lift

a simple machine that works via Pascal's principle

ideal fluid

hypothetical fluid used to make calculations simple

impulse

(J) change in momentum

index of refraction

(n) compares the speed (c) of light in a vacuum to the speed (v) of light in a particular medium

induction

a redistribution of electrical charge in an object, caused by the influence of nearby charges

inelastic collisions

lose some energy to internal energy

intensity (waves)

(I) the power of a wave

intensity level

(b) an intuitive scale of intensities based on the unit of decibels (dB)

Kirchoff's first rule

at any node (junction) in an electrical circuit, the sum of currents flowing into that node is equal to the sum of currents flowing out of that node

Kirchoff's second rule

the sum of the emfs in any closed loop is equivalent to the sum of the potential drops in that loop

lateral magnification (m)

Magnification of a lens or of an optical system, expressed as the ratio of the size of the image h′ to the size of the object h

mass defect

when proton + neutrons + electrons combine, the atom they form has less mass than the sum of the masses of the protons + neutrons + electron on their own; the difference is lost as energy

mechanical energy

kinetic and potential energy of macroscopic systems

mechanical wave

waves that obey the laws of classical physics; require a medium through which to travel; ex: water droplets, slinky, sound, ocean waves

modulus of elasticity

stress/strain

momentum

(p) a measure of a moving object's tendency to continue along its present path

node

point on two waves with the same wavelength traveling in opposite directions where there is no movement; also where the two waves collide

nonconservative force

change in mechanical energy when work is done; ex: kinetic frictional forces and the pushing and pulling forces applied by animals

Ohm's law

V= iR

Pascal's Principle

pressure applied anywhere to an enclosed incompressible fluid will be distributed undiminished throughout that fluid; think of a hydraulic lift

period

(T) the reciprocal of frequency; the number of seconds required for one wavelength to pass a fixed point

phase

relates to the wavelength, frequency, and place and time of origin; "a wave is either in or out of phase"

plane-polarized light

light that has only an electric field oriented in one direction

positron

like an electron with a positive charge (type of anti-matter)

positron emission

expulsion of a positron (type of radioactive decay)

power

rate of energy transfer; J/s or watt (W)

power (lenses)

the degree to which a lens, mirror, or other optical system converges or diverges light

random translational motion

motion of a fluid that contributes to fluid pressure (as in a fluid at rest)

resistance

the quantitative measure of an object of a particular shape and size to resist the flow of charge; measured in ohms

resonant frequency

(aka natural frequency) frequency at which a standing wave will resonate; if an outside driving force is applied to a structure at the resonant frequency, the structure will experience maximum vibration velocities and maximum displacement amplitudes

rms value

found by taking the square of all the terms, then taking the average, and then taking the square root

second harmonic

the second longest wavelength in a harmonic created by adding another node

shear modulus

modulus for shear stress

simple harmonic motion

motion that creates a sinusoidal function in time

specific gravity

the density of that substance compared to the density of water

standing wave

(aka stationary wave) a wave that remains in a constant position; can occur because the medium is moiving in the opposite direction or two waves are moving in opposing directions

strain

the fractional change in an object's shape; ratio of change in dimension compared to original dimension, so no units

stress

force applied to an object divided by the area over which the force is applied

torque

twisting force that will be clockwise or counterclockwise (at least on MCAT)

total internal reflection

an optical phenomenon that happens when a ray of light strikes a medium boundary at an angle larger than a particular critical angle with respect to the normal to the surface

uniform translational motion

motion of a fluid as a whole; doesn't contribute to fluid pressure

Universal Law of Conservation of Charge

the universe has no net charge

voltage

(V) given in volts; it is the potential for work by an electric field in moving any charge from one point to another

wave

the transfer of momentum and energy from one point to another

wave amplitude

(A) a wave's maximum displacement from zero; always positive!

wavelength

measured from any point in the wave to the point where the wave begins to repeat itself

work

transfer of energy using force; measured in joules

Young's modulus

modulus for tensile stress (E)

longitudinal wave

transverse wave

scalar

a physical quantity with magnitude but no direction

vector

a physical quantity with magnitude and direction

component vectors

two perpendicular vectors whose vector sum is equal to the original vector

Pythagorean Theorem

two common triangles

uniformly accelerated motion

motion with constant acceleration; both direction and magnitude of the acceleration must remain the same

three forces

1. gravitational
2. electromagnetic
3. contact

Newton's first law

law of inertia

Newton's second law

F = ma

Newton's third law

for every action there exists an equal and opposite reaction

frequency

number of full rotations per second (1/s)

centripetal force

force due to circular movement

equilibrium

no translational or angular acceleration; moving and rotating at a constant velocity

static equilibrium

equilibrium with a velocity of zero

dynamic equilibrium

equilibrium with constant, nonzero velocity

mechanical energy

the kinetic and potential energy of macroscopic systems

two types of energy transfer

1. work
2. heat

radioactive decay

atoms that spontaneously break apart

gamma ray

a high frequency photon that often accompanies the other decay types

nucleon

the proton and neutron

gauge pressure

a measure of pressure compared to local atmospheric pressure; local air pressure is arbitrarily given a value of zero

four conditions of an ideal fluid

1. no viscosity
2. incompressible
3. no turbulence
4. irrotational flow

surface tension

phenomenon due to intermolecular forces; can cause a needle to "float" on water

three types of waves

1. mechanical
2. electromagnetic
3. matter

two aspects of the medium through which a wave travels that affects the velocity

1. elasticity (resistance to change in shape)
2. inertia (resistance to change in motion)

resonance (waves)

condition where the natural frequency and the driving frequency are equal

direction of electric fields

positive to negative

direction of gravitational fields

towards mass creating the field

capacitor

used in a circuit to temporarily store energy in the form of separated charge (voltage)

direction of magnetic fields

north to south

electromagnetic wave

traveling oscillation of an electric and a magnetic field; ex: light

wavelengths of visible light

"ROYGBIV"

390nM
violet
indigo
blue
green
yellow
orange
red
700 nM

Linear Motion, V, Vo, a, t

V=V₀+at

Linear Motion, Δx, Vo, a, t

Δx=V₀t+1/2 a

Linear Motion, V, Vo, a, x

V²=V₀²+2aΔx

Linear Motion, Δx, avg. V, t

Δx=avgVt=t(V₀+V)/2

Force

∑F=ma, in newtons 1 N=1 kgm/s²

Weight

W=m*g, where g= 9.8 m/s²

Gravity

F=Gm₁m₂/r², where G is the gravitational constant

Gravitational Constant

6.67E-11 N*m²/kg²

Torque

τ=rFsinθ, where θ=angle between r and F

Kinetic friction

f=μN, where N=normal force and μ=friction coefficient

Centripetal Force

F=ma=mv²/r

Work

W=Fdcosθ, measured in Joules, 1 J=1 N*m

Power

P=W/t, measured in Watts, 1 watt=1 J/s

Kinetic Energy

KE=mv²/2, measured in Joules

Potential Energy

U=mgh, measured in joules

Momentum

p=mv

Impulse

J=F*t=Δp

Specific Heat

Q=mcΔT; only where there is no phase change

Heat of Transformation

Q=mL, where L is the heat required to change phase of 1 kg of substance

Pressure

P=F/A, in Pascals, 1 Pa=1 N/m²

Thermodynamic Work

W=PΔV

First Law of Thermodynamics

ΔU=Q-W, where ΔU is change in internal energy.

Density

ρ=m/v

Absolute Pressure of a Fluid

P=P₀+ρgh, where P₀ is pressure at the surface, h is depth of the point measured.

Pascal's Principle

ΔP=F₁/A₁=F₂/A₂
V=A₁d₁=A₂d₂
W=F₁d₁=F₂d₂

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