MCAT UWorld Physics Formulas/Units

pressure =

force/area

Hooke's law

F = -kx where k is the spring constant

power =

work / time

in watts, which is J/s

torque =

rFsin(theta)

elastic potential energy

(1/2)kx^2

electric field lines always point towards

negative charge

ions that take less time to reach detector in TOF-MS has smaller m/q ratio and

small radius of curvature in MS-MS

magnitude of uniform electric field =

change in voltage / distance of field

units are N/C or V/m

force exerted on a particle in an electric field (electric Lorentz force) =

qE

where q is charge and E is electric field strength

units are in N

force exerted on particle in magnetic field (magnetic Lorentz force) =

qvBsin(theta)

where q is charge, v is velocity, and B is magnitude of magnetic field

gases

diffuse passively across partial pressure gradient to reach equilibrium

positive pressure mechanical ventilator inflates lungs by directly

increasing alveolar pressure

normal inspiration causes

decrease in intrapleural pressure

passive expiration is possible due to

elastic recoil and surface tension (decreases alveolar volume and forces air out of the lungs)

violet light

refracts more than red light due to increase in frequency (higher refractive index)

lens strength/optical power =

1/f

units = diopters, which is inverse m

radius of curvature =

2focal lengths

state function

describes equilibrium state of system, independent on path taken. include pressure, volume, temperature, thermodynamic variables (entropy)

path functions

describes path taken by system to transition from one equilibrium state to another. ex. are heat and work

amount of work done on system =

pressure x change in volume

conduction

transfer of heat through DIRECT PHYSICAL CONTACT

convection

transfer of heat through movement of fluids (or gases)

radiation

transfer of heat through emag radiation

heat capacity (C) =

mass x specific heat capacity (c)

the mc in the q = mc delta T

systolic pressure is

maximum blood pressure in arteries

diastolic pressure is

minimum blood pressure in arteries

volumetric flow rate/cardiac output =

stroke volume (amount of blood ejected from LV in one cycle) x heart rate

Hz is

1 cycle/second

pressure difference =

CO x VR

cardiac output x vascular resistance

volumetric flow rate =

cross sectional area x flow velocity

group of vessels that has the greatest resistance is the group that hase

the greatest pressure drop

Pascal's law

F1/A1 = F2/A2

mechanical advantage =

Fout/Fin

or

din/dout

specific heat of substance =

amount of heat required to increase 1 g of substance by 1 degree C

center of mass shifts in same direction as

redistribution of mass

if astronaut strikes protrusion after traveling in straight path with same velocity

generates torque, making the astronaut spin about the CM

tensile forces can lead to

elongation of objects under tension

translational motion equation when initial velocity is same and you are are just looking at vertical motion

t = 2vinitial / g, or 0

where t is time

time of flight is inversely proportional to acceleration of gravity

sound

attenuates most in soft materials, is a pressure/longitudinal wave

1 MHz

10^6 Hz

doppler effect equation

f' = f (V +/- Vd)/ (V -/+ Vs)

where V = speed of sound in the medium

Vd = speed of the detector

Vs = speed of the source

Top sign: toward (if source or detector is moving toward other)

Bottom sign: away (if they moving away from other object)

*Treat numerator and denominator separately when deciding if top or bottom sign

doppler effect magnitude of freq shift

delta f / f = v/c

where v is the relative velocity between source and observer, and c is speed of wave in the medium - this is why ultrasound has larger freq shift than IR, since IR travels at speed of light and US travels much slower (c is smaller so shift is bigger)

weight is

FORCE of gravity on an object = mg

archimedes principle

density of object / density of liquid = Fgravity / Fbuoyant

specific gravity =

density of substance/density of water

vol displaced (submerged) / total volume

object (i.e. brain inside skull) continues to move due to

inertia, which could cause injury to opposite side of head

WEIGHT is

the gravitational force exerted on an object's mass

shear force is proportional to

dynamic viscousity (change in velocity / change in location)

kinetic energy of flow is

dissipated by frictional sharing forces

parallel resistors:

- voltage drop across each resistor is the same (equal to the voltage generated by battery)

- equivalent resistance decreases if resistor is added in parallel

- current through each resistor is independent from that through other resistors

energy stored in capacitor (U)

(1/2)CV^2

where C is capacitance and voltage is V

current and resistance are

inversely proportional

Power (P) =

current (I) x voltage (V)

C/s x J/C

work associated with expansion or contraction of gas is known as

P x delta V

when sound moves from air to liquid

velocity INCREASES, intensity DECREASES

properties of medium for sound propagation:

- velocity increases with temperature

- velocity is slowest in gases, then liquids, fastest in solids

- within a phase of matter, velocity increases with stiffness and decreases with density

when sound moves from one medium to another, portion of energy is reflected, causing decrease in

intensity

Resistance (R) =

R = ρL/A

(ρ is the constant of resistivity)

Capacitance (C) =

Q/V

also, k (dielectric constant) x Co (capacitance of vacuum)

also, is proportional to Area / Distance between plates

changing resistance

placing multiple resistors in series increases resistance, placing multiple resistors in parallel decreases resistance

changing capacitance

placing multiple capacitors in series decreases capacitance, placing multiple capacitors in parallel increases capacitance

frequencies of harmonics

fundamental frequency x harmonic number (where fundamental freq is 1st harmonic)

i.e. if fundamental freq is 100, 3rd overtone is 100 x 4 = 400 Hz

electric field lines

run towards NEGATIVE CHARGES. do not indicate direction of travel

ex. in gel electrophoresis, the electric field lines point towards the negative cathode (where the negative charges start)

F = qE

Equation for the force felt by a charged particle in an electric field

particle's MASS DOES NOT AFFECT THIS

diffraction

The bending of a sound wave as it moves around an obstacle or passes through a narrow opening

first law of thermodynamics

Q = delta U + W

heat added or taken away = change in internal energy + work done by system

difference between heat absorbed by object and work done by object

speed decreases

what happens when pressure waves move through boundary into air

*speed changes when medium changes

force on object

force doing work on object should be:

arm is horizontal

most torque extended on shoulder is when

*you want the lever arm to be perpendicular, not parallel