MCAT Physics Flashcards
kinematics equations
V = at + Vo
X = 1/2 a t^2 + Vo t + Xo
∆X=1/2 (Vo+V)t
V^2 = 2a∆X + Vo^2
force of gravity
F = G (m1m2)/r^2
angular symbols
∅ = x (radians or degrees
w = v
α = accelaration
T = torch = force
I = moment of inertia = center of mass
L = angular momentum = momentum
linear to angular equations
v = rw
a = rα
a = v^2/r
KE = 1/2mv^2 = Iw^2
s=r∅
torch
T = F*r sin∅
T = rma = rm(r∝)=r^2 m∝=αI
angular momentum
(L)=(mv)r=Iw I=mr^2
degrees to radians
degrees(π) = radians(180)
Spring
F = k * 1/2x
W = k * 1/2x^2
compression 3 - 8 inches : W = k* 1/2 (8^2 - 3^2)
center of mass
((Σmx/Σm))/Σx=center mass ratio
Multiply by the length of the object to find the location of the center of mass
conservation of momentum
mv=mv
fluids
p = m/V
buoyant F = pVg (pV = m)
weight of liquid displaced P = Po + pgh
F1/A1 = F2/A2
Bernoulli: P1 + pgh + 1/2pv^2 = P2 + pgh + 1/2pv^2
∆V/∆t = π/8 (r^4/n) (p1-p2)/L
n = viscosity P = pressure surface tension Y = F/L
speed of a wave
v = λf
speed of wave on string=(Ft/u)^(-2)
Ft = tension force u = mass/length
Speed of sound faster when molecules are closer together Ultrasound = 20,000Hz + infrasound = 20Hz -
de/constructive interference
constructive = phase of the wave lines up and increases in amplitude destructive = waves are out of phase and cancel each other out
power sound
P = I(4πr^2)
Intensity by the surface area of the sphere with the radius equal to the distance
decibels
dB = (10dB)log I/Io
increasing intensity by factor of 10 doubles the loudness Io=1x10^(-12) W/m^2
doppler effect
change in frequency when source or observer are moving towards/away from each other
f’ = f (v+/-vo)/(v+/-vs)
moving towards each other = increase frequency moving away from each other = decreased frequency
harmonic motion
F=-kx
motion of spring: x = A x sin(2πt/T) = A x sin(2πft) = A x sin(wt)
w= angular frequency = (k/m)^(-2) energy:
E = 1/2mv^2 = 1/2kA^2 (A = amplitude)
energy equations
Total E = KE + PE
KE = 1/2mv^2 = 1/2kA^2 (harmonic A = amplitude)
KE = Iw^2 (angular motion)
PE = mgh W = k * 1/2x^2 (spring)
induction
inducing a charge in a object without touching it
electric field & voltage equations
F = 1/(4πεo ) x (q1 q2)/r^2
E = F/q = (1/(4πε0 )) x q/r^2
V = (1/(4πε0 ))*q/r Va-Vb = Wab/qo
electric field vs voltage
Vb-Va = Wab/qo E = delta(V)/delta(s)
electric field = amount of force a particle would experience per unit charge voltage = when force is not constant, amount of work to move 1 unit positive charge between A and B.
flux
ΦE=EA charge per m^2 (charge through an area)
q = ε0EA A = (4πr^2) sphere
current
I = Q/t = ∆q/∆t = nA(eV)
n= density charge
Current density j = i/A = nA(ev)
circuits equations
V=IR P = VI = V^2/R
P = I^2 R(heat loss)
R = p(L/A) p = resistivity AC
Power P = (Vmax Imax)/(2)^.5 C = Q/V = (ε0 A)/d
Resistance
R = p(L/A)
p = resistivity
V=IR P = VI = V^2/R P = I^2 R(heat loss)
capacitor
ability to store charge. build up of charge on a plate causing the opposite charge to accumulate on the other plate. measured in farad.
C = Q/V = (ε0 A)/d increase c with shorter distance between plates and more area. ε0 = 8.9x10^-12 F/m
ε0
ε0 = 8.9x10^-12 F/m
AC/DC current
direct current/alternating current average of sin wave = root mean square of maximum
Pavg = Vmax/2^.5 x Imax/2^.5 diode
converts AC to DC (only allows current to flow in 1 directions) half/full wave rectifier - diodes.
generator
rotating coil in a magnetic field induces a current to oppose the change in magnetic field through the wire as it rotates. make it stronger by: increase number of turns in coil rotate coils faster use stronger permanent magnets add soft Iron core in the coil to increase the magnetic field
parallel and series
parallel: C = C1 +C2 +C3… R = 1/R1 + 1/R2 + 1/R3….. series: C = 1/C1 + 1/C2 + 1/C3….. R = R1 + R2 + R3…..
magnetic force
F = qvB = 1/2mv^2 (centripetal F when charge moves in circle)
RHR: qv (hand) B(fingers) F (thumb)
mass spectrometer equation
breaks molecules into ions and shoots through magnetic field and measure the amount of bend in trajectory.
m = (qB^2r^2)/(2V)
magnetic field and current
RHR: current (thumb) magnetic field (fingers)
B = (Uo*I)/(2πr)
solenoids
loop of wire conducting a current that creates a strong magnetic field in the center of the loop. The strength depends on the number of loops (N)
first faraday’s law
magnet through a loop: current only occurs when the magnet is moving current is directly proportional to the strength of the magnet and the speed direction of the current depends on the N-S orientation
second faraday’s law
a loop with a battery next to a sensing loop with a galvanometer current seen only during opening or closing of switch induced current is proportional to the number of loops in either and the rate of change in current in the driving coil
lenz’s law
current induced in a loop creates a magnetic field that opposes the change in magnetic field through the loop
light equations
n1 sinΦ1 = n2 sinΦ2
n=c/Vmedium
n= index of refraction
dispersion
prism effect from index of refraction (n) being different for different wavelengths n1 sinΦ1 = n2 sinΦ2
polarization
light with electric vectors going in same direction orientation of light wave (magnetic and electric field are at right angles) ^ electric field ^ o direction >magnetic field o >
reflect/refract polarization
light polarizes when angle of reflection and refraction are 90 degrees n(air)
sin⍬=n(water)
cos⍬ and tan⍬ = n(water)/n(air) if water and air ⍬ = 53
diffraction
what happens when light hits an object single and double slit: light must be polarized and have a single frequency
double slit
Y(m)/L=mλ/d
sin⍬=mλ/d
d = distance between slits
m = 1 constructive m = .5 destructive
single slit
Y(m)/L = mλ/a
sin⍬ = mλ/a
a = width of opening
m = .5 constructive m = 1 destructive
lense and mirror equations
1/o+1/i=1/f f=r/2 M=h(o)/h(i) =-i/o
mirrors
lateral inversion, virtual image front = + back = -
concave mirror )
inverted, closer o is to f the farther away i is, i is always positive
convex mirror (
up-right, closer o is to mirror the closer i is to mirror, i is always negative
converging lenses ()
f = + (between f-2f =>magnified other side)
(between f-m => same side)
diverging lenses )(
f = - image on same side
electron radii
r = (hεo)/(πme^2 ) n^2
r =ao n^2 ao = ??
quantum energy
En = 13.6ev/n^2
(Ei-Ef)/h =13.6ev/h * (1/(nf^2 ) - 1/(ni^2 ))
energy at radii n
En = 13.6ev/n^2
energy emitted by change in radii
f = (Ei-Ef)/h =13.6ev/h * (1/(nf^2 ) - 1/(ni^2 ))
plank’s constant
h = 6.636 10^-34 Js h = 9.14 10^-15 eVs
fission
heavier nuclei splitting and releasing energy in the form of heat
fusion
two nuclei fuse together, specific elements release energy
radioactive decay
R = (delta)N/t = λN
λ = proportionality constant (+ = growth, - = decay)
N=No e^ λt (N = daughter, No = parent)
T = -ln2/ λ
R = Ro r^n
half life
T = -ln2/ λ
decay particles
alpha (α 4 ^2) beta (β 0 ^(+/- 1)) gamma (γ 0^0)
amount of decay material
N=No e^ λt (N = daughter, No = parent)
radiation per second
R = Ro r^n
n = number of counts
r = distance from source
Ro = initial radiation per second
