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Thursday, September 27, 2012

MCAT Physics Equation Lists (Formulas)


MCAT Physics Equation Lists (Formulas)

MCAT Physics Equation Lists (Formulas)

Memorize These!

Translational motion x = x 0 + v 0 t + at2/2 Vƒ = Vo + at
Frictional force max = μ Ν μk < μs
Uniform circular motion Fc = mac = mv2 /r ac= v2 /r
Momentum, Impulse I = F Δt = ΔM M = mv
Work, Power W = F d cosθ P = ΔW/Δt
Energy (conservation) ET = Ek + Ep E = mc2
Spring Force, Work F = -kx W = kx2 /2
Continuity (fluids) A v = const. ρAv = const.
Current and Resistance I = Q/t R = ρL/A
Resistors (series, par.) Req = R1 + R2 . . . 1/ Req = 1/ R1 +1/ R2
Sound dB = 10 log 10 (I/I0 ) beats = Δ f
Kirchoff's Laws Σ= 0 at a junction  ΣΔ= 0 in a loop
Thermodynamics Q = mc Δ T             Q = mL
Torque forces L1 = F1× r1 L2 = F2 × r2
Torque force at EQ ΣFx = 0 and ΣFy = 0

Σ= 0

Refraction sin θ1 )/(sin θ2 ) = v1 /v2 = n2 /n1 = λ1 /λ2 n = c/v

Memorize as Pairs


F = ma


F = qE

Similar Form
F = KG m1 m2 r2 ) F = k q1 q2 r2 )  
V = IR P = IV Paired Use
vav = Δ d / Δ t aav = Δ v / Δ t (avg vel, acc)
v = λ f E = hf (f = 1/T)
Ek = ½mv2   Ep = mgh (kin, pot E)
Ρ = F/A Δ Ρ = ρgΔh (pressure Ρ)
SG = ρ substance / ρ water ρ = 1 g/cm3 = 103 kg/m3 (Spec Grav)
ρ = mass / volume Fb = Vρg = mg (buoyant F)
Irms = Imax / √2 Vrms = Vmax / √2 Root Mean Sq
1/ + 1/ = 1/ f = 2/r = Power magnification = - i/o Optics

Note: Specific gravity (SG) is equivalent to the fraction of the height of a buoyant object below the surface of the fluid.


Don't Memorize, Know How to Use...

Ρ + ρgh + 1/2 ρv2 = constant

Bernouilli's Equation Fluids in Motion
L0 (1 + αΔ ) Linear Expansion Solids, Temp Δ
A0(1 + γΔ ) Area Expansion  

V0(1 + βΔ )

Volume Expansion β = 3 α
fo = fs (V ± vo )/ ( ± vs ) Doppler Effect: when d is decreasing use + vo and - vs  
Ed for a parallel plate capacitor = the distance between the plates  
dF = dq v(B sin α) = I dl(B sin α) Laplace's Law RH rule
1/ Ceq = 1/ C1 + 1/ C2 + 1/ C3 . . . Capacitors in Ser. and Par. Ceq C1 C2 . . .
Potential Energy ( PE ) = = 1/2 QV Work in Electricity = 1/2 CV2
ΔG = ΔH - TΔS Gibbs Free Energy ΔG° = -RTln Keq
     

Atomic Physics


1) alpha (α) particle = 2He4 (helium nucleus);

2) beta (β) particle = -1e0 (an electron);

3) a positron +1e0 (same mass as an electron but opposite charge);

4) gamma (γ) ray = no mass, no charge, just electromagnetic energy;

5) Δ /Δ = rate of decay where Δ = change in mass, Δ = change in time.

6) If the number of half-lifes are known we can calculate the percentage of a pure radioactive sample left after undergoing decay since the fraction remaining = (1/2) n .

Nelectrons = 2 n2 , where Nelectrons designates the number of electrons in shell .

The state of each electron is determined by the four quantum numbers:


  • principal quantum number n determines the number of shells, possible values are: 1 (K), 2 (L), 3 (M), etc...

  • angular momentum quantum number l, determines the subshell, possible values are: 0 (s), 1 (p), 2 (d), 3 (f), n-1, etc...

  • magnetic momentum quantum number ml , possible values are: ± , ... , 0

  • spin quantum number ms ,determines the direction of rotation of the electron, possible values are: ±1/2.

The Basics


Right Triangles

sin θ = opp/hyp

cos θ = adj/hyp tan θ =opp/adj
θ = sin -1 x arcsec θ = sec-1θ r2 = x2 + y2

  • angle θ may be given in radians (R) where 1 revolution = 2πR = 360°

  • estimate square root 3 as 1.7 and root 2 as 1.4

  • cross-sectional area of a tube = area of a circle = πr2 where π can be estimated as 3.14 and is the radius of the circle; circumference = 2πr

Some Units to Memorize



  • Both work and energy are measured in joules where 1 joule (J) = 1 × 1 . {Imperial units: the foot- pound , CGS units: the dyne-centimeter or erg }

  • The SI unit for power is the watt (W) which equals one joule per second (J/s) = volts × amperes .

  • Current is measured in amperes = coulombs/sec. The units of resistance are ohms, symbolized by Ω (omega), where 1 ohm = 1 volt/ampere.

  • The SI unit for pressure is the pascal (1 Pa = 1 N/m2 ). Other units are: 1.00 atm = 1.01 × 105 Pa = 1.01 bar = 760 mmHg = 760 torr.

  • The SI unit for the magnetic induction vector is the tesla where 1 T = 1 N/(A)(m) = 104 gauss.

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