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Physics Formulas Flashcards

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14374078844Dot Product A*B=|A||B|cos theta0
14374078845Cross Product AxB=|A||B|sin theta1
14374078846Gravitational Force Fg=Gm1m2 / r^2; G= 6.67x 10^-11 N*m^2/kg^22
14374078847Kinetic frictionfk= (mu)k * Normal Force (N)3
14374078848Relationship between static and kinetic friction0<=fs <= (mu)s * Normal force4
14374078849Center of gravityx=(m1*x1 + m2*x2 + ....+ mnxn)/(m1 + m2 +....+ mn); Do the same for y and z5
14374078850Average Accelerationa= deltav/deltat6
14374078851Instantaneous accelerationa= lim (deltav/deltat) as t->0; a= dv/dt7
14374078852Kinematics with vf, vi, a, and tVf=Vi + a* t -> (m/s) = (m/s) + (m/s^2)*(s)8
14374078853Kinematics with x, Vi, t, and aX= Vi*t + (1/2)*a*t^2 -> (m)= (m/s)*(s) + (1/2)*(m/s^2)*(t^2)9
14374078854Kinematics with Vf, Vi, a, and XVf^2 = Vi^2 + 2*a*x -> (m^2/s^2) = (m^2/s^2) + 2*(m/s^2)*(m)10
14374078855Kinematics with X, V, and tX= Vt -> (m) = (m/s)*(t)11
14374078856Centripital ForceFc = (mv^2)/r = m * centripital acceleration = m * v^2/r12
14374078857Centripital accelerationv^2/r13
14374078858Period of circular motionT= (2*pi*r)/v -> v= (circumference)/time14
14374078859Angular Speed of circular motionw= (2*pi)/ T -> w= v/r by substituting T. Makes sense as 2pi radians is a full circle15
14374078860torquetorque = r x F = rFsintheta16
14374078861Kinetic EnergyKE= (1/2)*m*v^217
14374078862Gravitational potential energyU = m*g*h18
14374078863Elastic Potential EnergyU = (1/2)*k*x^2; where k is the spring constant and x is the magnitude of displacement19
14374078864Work done by nonconservative forcesWnonconservative = Delta E = DeltaU + DeltaK; Where U is potential energy and K is kinetic energy20
14374078865Work FormulaForce * Distance = Fdcostheta; Unit is Joule = (kg*m^2)/s^2)21
14374078866Power FormulaP = W/t = DeltaE/t; Amount of work done per unit time;22
14374078867Net Work formulaWnet = DeltaK = Kf - Ki23
14374078868Mechanical AdvantageFout/Fin24
14374078869EfficiencyWout/Win = load * load distance / effort * effort distance; load distance may not equal effor distance25
14374078870Work in isobaric systemW= P* DeltaV; Using P= F/A this makes sense. Units being N*m26
14374078871Work from a P-V GraphWork = area under curve27
14374078872Farenheit and Celsius ConversionF=(9/5)C+3228
14374078873Celsius and Kelvin ConversionK = C + 27329
14374078874Linear Expansion EquationDeltaL = alpha*L*DeltaT; alpha is the coefficient of linear expansion30
14374078875Volumetric Expansion EquationDeltaV = Beta*V*Delta T31
14374078876Coefficient of volumetric expansion (Beta) from coefficient of linear expansion (alpha)Beta = 3* Alpha32
14374078877Change in Systems internal Energy EquationDelta U = Q - W; Q is energy transferred into the system as heat, W is the work done by the system33
14374078878Heat Transfer Equation and what its used forq = m*c*DeltaT; where c is the specific heat; mass is grams; Used for calorimetry34
14374078879Formula for Heat of Transformationq = m*L; where L is the heat of transformation or latent heat, usually given35
14374078880Change in Entropy EquationDeltaS = Q(rev)/T; where Q is the heat gained or lost in a reversible reaction36
14374078881Specific GravityDensity substance / Density of water; Density of water = 1g/cm^3 or 1000 kg/m^337
14374078882Absolute (Hydrostatic) PressureP = Po + density*g*depth; Check units. P= F/A (N/m^2); where Po is the pressure at surface38
14374078883Pgauge formulaPgauge = Pabs - Patm; i.e. the difference in pressure between surface and object39
14374078884Bouyant ForceFb= density(fluid)*V(fluid displaced)*g = density(fluid)*V(submerged)*g40
14374078885Ratio of object submergedRatio = density of object/ density of fluid; Can be derived from sum of forces on floating object41
14374078886Rate of laminar flowQ=(pi*r^4*DeltaP)/(8*n*L); where n is the viscosity42
14374078887Critical speed of fluid flowVc = (Nr*n)/(density*D); where Nr is Reynold's number and is usually given; at this speed we go from laminar to turbulent flow43
14374078888Flow rate with respect to linear speed and areaQ (flow rate) = V1A1 = V2A2; units work out such that it's m^3/s44
14374078889Bernoulli's EquationStatic Pressure 1 + Dynamic Pressure 1 = Static Pressure 2 + Dynamic Pressure 2; P +density*g*h + (1/2)*density*V^2 = Same thing on other side45
14374078890Force on a chargeFe = (kQq)/r^2; where k is coulomb's constant (aka electrostatic constant) OR Fe = qE46
14374078891Magnitude of an electric fieldE = (Fe/q) = Force felt by test charge / test charge Or E = (kQ)/r^2 where Q is the source charge47
14374078892Electric Potential EnergyU = (kQq)/r; Makes sense as Delta U=W = Fdcostheta = F*d = [(kQq)/r^2]*r48
14374078893Electric Potential EquationV= kQ/r49
14374078894Work done by moving a charge across an electric fieldWab = qDeltaV50
14374078895Dipole Momentp = q*d51
14374078896Torque of a dipole in electric fieldT1=F*r*sintheta -> T1=qE*r*sin(theta) -> Total torque = 2*qE*r*sin(theta) = qE * d * sin(theta) = pEsin(theta)52
14374078897Potential energy of Dipole in electric field***U = -p*E*cos(theta)*** Zero at 90 degrees because at 180 degrees it is at maximum and at 0 degrees it is at minimum53
14374078898Magnetic Field for straight wire @ any distance r from the wireB = (mu*I)/(2*pi*r)54
14374078899Magnetic Field for a circular loop @ center of loopB = (mu*I)/(2*r)55
14374078900Magnetic force on charge in fieldF = qvBsin(theta)56
14374078901CurrentI = Q/Deltat57
14374078902ResistanceR = (resistivity (rho) * L) / A58
14374078903Ohm's LawV = IR59
14374078904True voltage of a circuitV = Ecell - i*r(int); where Ecell is emf, r(int) is the internal resistance60
14374078905Power in circuitP = IV = I^2*R = V^2 / R61
14374078906Resistors in seriesAdd62
14374078907Resistors in parallelAdd inversely63
14374078908Capacitors in seriesAdd inversely64
14374078909Capacitors in parallelAdd65
14374078910Capacitance of a parallel plate capacitorC = Eo*(A/d); where Eo is the permittivity of free space = 8.85 x 10^ -12 (F/m)66
14374078911Uniform electric field across a parallel plate capacitorE = V/d67
14374078912Voltage across an electric fieldV = E x r -> V=E*d for a parallel plate capacitor68
14374078913Potential energy of a capacitorU = (1/2)*C*V^269
14374078914Capacitance of a capacitor with a dielectric materialC' = kC -> C=k * (Eo) * (A/d) -> C = (A*k*Eo) / d70
14374078915propagation speed of a wavev = f*lambda71
14374078916Period of a waveT = 1 / f72
14374078917Angular frequency (w)w = 2*pi*f = (2*pi) / T73
14374078918Speed of SoundSqrt(B/density); where B is the 'bulk modulus' and density is that of the medium74
14374078919Doppler Equationf ' = f [ (V +- Vd) / (V -+Vs) ]; Use 'left' if detector or source is moving toward the other. Use 'right' if detector or source is moving away from the other75
14374078920Sound intensityP/A where A is surface area76
14374078921Surface area of a sphereA = 4*pi*r^277
14374078922Sound Level FormulaB = 10 log (I / Io); where B is measured in dB, I is intensity of the sound wave and Io is the threshold of hearing (1x10^-12 W/m^2)78
14374078923Altered Sound Level FormulaBf = Bi + 10 log (If / Ii); Can be derived from Sound Level Formula (DeltaB)79
14374078924Given string fixed at two ends: What are the lengths that correspond to each harmonic? (1st, 2nd, and 3rd)They are L = (1/2)lambda, lambda, (3/2)lambda; We can draw them. # of ANTINODES = Harmonic #. Use equation L=(A.N./2)*lambda where A.N is # of Antinodes80
14374078925Given a pipe open on both ends: What are the lengths that correspond to each harmonic? (1st, 2nd, and 3rd)They are L = (1/2)lambda, lambda, (3/2)lambda; We can draw them. # of NODES = Harmonic #. Use equation L=(N/2)*lambda where N is # of Nodes81
14374078926For a string fixed on both ends and an open pipe (one that's open on both ends), What are the frequencies for each harmonicf = (n*v) / (2*L) where n is the harmonic #; i.e. number of A.N. in fixed string, and number of N for open pipe82
14374078927For a closed pipe (One that is closed on one end), what are the lengths that correspond to each harmonic?The only harmonics of a closed pipe are odd harmonics. Use formula L= lambda * [(N + A.N.-1) / 4]; Numerator corresponds to the harmonic83
14374078928For a closed pipe (One that is closed on one end), what are the frequencies that correspond to each harmonic?f = (n*v) / (4*L) where n is the harmonic # -> Harmonic # = ( N + A.N. -1)84
14374078929Speed of light formulac=f*lambda85
14374078930Law of reflectionTheta1 = Theta2; Theta is with respect to the normal vector86
14374078931Focal lengthDistance from mirror to Focal Point (F); f = r/2; where r is the radius of curvature87
14374078932Distance between Object (O) and mirror is'o'88
14374078933Distance between Image (I) and mirror is'i'89
14374078934Distance between Center of Curvature (C) and mirror'r'90
14374078935Distance between Focal Point (F) and mirror'f'91
14374078936Equation for mirrors and lenses(1/f) = (1/'o') + (1/i) = (2/'r')92
14374078937If i is positiveThe image is real - image is on "same side as you"93
14374078938If i is negativeThe image is virtual - image is "on the side opposite of you"94
14374078939If o is positiveObject is in front/on the light source side95
14374078940If o is negativeObject is behind/on the opposite side of light source96
14374078941Equation for plane mirrori = -o; Plane mirrors essentially have an r that is infinity97
14374078942Equation for magnificationm = -i / o; If |m|<1 then the image is smaller than object. If |m|>1, then image is magnified; m<0 then inverted; m>0, upright.98
14374078943Positive r is alwaysconverging99
14374078944Negative r is alwaysdiverging100
14374078945Converging mirror isConcave101
14374078946Diverging mirror isConvex102
14374078947Converging lens isConvex103
14374078948Diverging lens isConcave104
14374078949Index of refraction equationn = c/v; where n is the index of refraction, c is the speed of light, and v is the new speed105
14374078950Snell's Lawn1sin(Theta1) = n2sin(Theta2)106
14374078951If n1>n2(Theta2 / Theta 1) must be >1 i.e. Theta 2 > Theta 1 --> Bends away from normal107
14374078952If n1(Theta2 / Theta 1) must be < 1 i.e. Theta 2 < Theta 1 --> Bends toward normal108
14374078953Critical Angle of incidenceThetac = sin^-1(n2/n1); Can be derived from snell's law with Theta2 equal to 90 degrees109
14374078954Lensmaker's Equation(1/f) = (n-1) * [(1/r1)-(1/r2)] - Used when width of the lens is not negligable110
14374078955Power of a lens equationP = 1/f111
14374078956index of refraction equation w/ regards to chromatic aberrationn = c/v; n = c / (lambda * f); in the new medium f is maintained, but lambda is changed.112
14374078957Double Slit light fringes equationdsin(theta) = m * lambda; where d is the distance between the slits, theta is the angle between 0th light fringe and the desired light fringe113
14374078958Single Slit Dark Fringes equationasin(theta) = m * lambda; where a is the slit length, theta is the angle between the 0th light fringe and the desired dark fringe114
14374078959Thin Film Constructive interference formula (assuming pi shift i.e. n12*n2*t = (m + .5)*lambda; where n2 is the index of which light is entering, t is the thickness of the film, m is the multiple of which constructive interference would occur, and lambda is the wavelength of light prior to entering115
14374078960Thin Film Destructive Interference Formula (Assuming pi shift i.e. n12*n2*t = m*lambda; where n2 is the index of which light is entering, t is the thickness of the film, m is the multiple of which destructive interference would occur, and lambda is the wavelength of light prior to entering.116
14374078961Kinetic Energy of an electron from photoelectric effectKEmax = E(photon) - W -> KEmax = hf(photon) - hf(threshold); Thus once f >f(t), the frequency of the photon is directly proportional to the KE of the resulting electron. Also can be written as KEmax = h(c/lambda) - hf(threshold)117

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