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MCAT Physics (VL)

QuestionAnswer
Coulomb's constant (K0) 9*10^9 Nm^2/C^2
Pythagorean triples 3, 4, 5 5, 12, 13 7, 24, 25
Big Five for free fall d = V0 + 1/2at^2 vf = v0 + at vf^2 = v0^2 + 2ad d = 1/2(v0 + vf)t
Triangle with 30 and 60 degrees sqrt3, 1, 2
Triangle with 45 degree 1, 1, and sqrt2
sqrt2 1.4
sqrt3 1.7
F(grav) F(grav) = GMm/r^2
Gravitational acceleration g = GM/r^2
Max coefficient of static friction ? coefficient of kinetic friction Max coefficient of static friction ? coefficient of kinetic friction
3/2 1.5
Center of mass with point masses Center of mass (x) = [x1m1 + x2m2 +...]/[m1 + m2 +...] EVEN IF THE STICK IS HOMOGENOUS, ITS CENTER OF MASS NEEDS TO BE INCLUDED
Center of gravity Same as center of mass but replace m by weights
Centripetal force F(c) = ma(c) = mv^2/r
Centripetal acceleration a(c) = v^2/r
What is Fc? (Definition) Fc is what the forces towards the center add up to. It is not a force like gravity and others that are added to diagrams
Name for the center of a rotating object which stays in place Pivot point or fulcrum
Torque. What is the radius vector? From fulcrum or pivot point to where the force was applied
Torque t=rFsin0 or t=lF
Torque. Lever arm. Shortest distance between pivot and extended line where the force acts. rsin0 = l
Unit for torque t= Fsin0r so units are N*m. Labeled CCW or CW.
Two types of equilibrium Translational (Fnet=0) and rotational (tnet=0)
Inertia Resistance to acceleration. An object's mass measures its translational inertia.
Torque net in terms of rotational inertia t(net)=Ia I is rotational inertia. a is acceleration
When is rotational inertia higher When the average mass of the object is further away from the axis of rotation. Smallest when the rotation axis passes through the object's center of mass.
Centripedal force vs. centrifugal Centrifugal is the tendency for the object to fly away from center of curvature. Centripedal force in the net force pointing inwards.
Work by a constant force W=Fdcos0 0 is angle between force and the distance
Units for work N*m --> Joule
Power Work/time = Fv (when force is parallel to d)
Power units J/s or watts (W)
Work-energy theorem W = deltaKE
Units for KE Joule. KE equals work
Types of PE Gravitational, electrical and elastic
DeltaPE(grav) = DeltaPE(grav) = -W(by the force of grav) = mgh
Conservation of total ME with outside force KEi + PEi + W(by friction) = KEf + PEf
What are simple machines? Tools that allow us to accomplish same task with less force, but work is still the same. Distance must increase to compensate for less work.
Mechanical advg. Quantification to show how much less force is required. Mechanical Advg = effort distance/resistance distance * MA = Distance you end up moving the thing divided by the distance you would've had to move it without the tool
Efficiency (%) of a simple machine Measures how much friction and other factors reduce the actual work output from the theoretical macimum Efficiency = W(output)/Energy(input)
Linear momentum p = mv. It is a vector pointing in direction of v.
Impulse-momentum theorem J(impulse) = deltap=delta(mv)=Fdelta(t)
Area under the curve is equal to Axis X * Axis Y
Elastic collisions Total momentum and total KE conserved ON THE MCAT DON'T ASSUME COLLISION OF MACROSCOPIC OBJECTS IN ELASTIC
Inelastic collision Total momentum conserved but not KE
Perfectly inelastic collision Inelastic condition where objects stick together. Momentum conserved, KE not.
angular momentum (L) L =lmv = Iw l is the distance between center and particle (radius). I is rotational inertia and w is angular velocity.
Rate of change of momentum Linear momentum: J=deltaP=Fdelta(t) F=deltap/delta(t) t = delta(L)/delta(t) Force is the rate of change of linear momentum and torque is the rate of change of angular momentum If the total force is zero or total torque is zero then L and p don'
Density of water (Kg/m^3) 1000
Specific gravity density of substance/density of water
Pressure Force/area Force must be perpendicular to area Scalar value
Unit of pressure N/m^2 or pascal
Hydrostatic gauge pressure P(gauge) = p(fluid)gD p is density of the fluid D is depth of material Hydrostatic because fluid is at rest and Gauge because atm pressure not accounted
Archimedes principle (buoyancy) Magnitude of buoyant force is the weight of the fluid displaced by the object
Buoyancy F(buoy) = p(fluid)V(sub)g
Floating object in equilibrium on surface w object = F(buoy) V(sub)/V = p(object)p(fluid) If 3/4 less density of fluid then 3/4 will be above water
W object and F buoyancy W(object)/F buoyancy = p(object)/p(liquid if water then = specific gravity
Apparent weight W(apparent) = w-Fbuoy
Pascal's Law (Concept) Pressure changes in a fluid will be spread evenly throughout the fluid in a closed container
Pascal's Law (Equation) F1/A1 = F2/A2 If A2 is bigger than A1, then F2 is stronger but again must increase distance for work to be constant
Area and distance with Pascal A1d1=A2d2 (because volumes have to be the same) F2d2=F1d1
Force of surface tension F=2yL (L is the length), y is coeff of surface pension (force per unit length)
Flow rate f=Av A of cross sectional Flow rate must remain constant through a pipe so A1v1 = A2v2
Continuity (flow) equation Flow rate must remain constant through a pipe so A1v1 = A2v2
Conditions for Bernoulli's Equation (Ideal fluid) Icompressible Negligible viscosity Laminar flow Steady flow rate
Opposite of laminar flow Turbulent flow
Bernoulli's equation (concept) Conservation of total ME for ideal fluid flow
Bornoulli's equation (equation) P1 + 1/2pv^2 + pgy = P2 + 1.2pv^2 + pgy2 Y is height of pipe from arbritary horizontal reference. P pressure and p is density of flowing fluid.
Torricelli's results V efflux of liquid v(efflux) = sqrt(2gD) D is distance from surface of liquid to hole
Bernoulli effect or Venturi effect Pressure is lower where flow speed is greater
Three type of forces on an object tension, compression and shear
Stress Stress = Force/Area If circle, inversely proportional to the square of the cross-sectional radius or diameter
Diff. between stress and pressure Stress doesn't have to be perpendicular (in shear force is parallel)
Strain (concept) Ratio of appropriate change in the length to the original length Stress causes strain
Strain (equation) Tensile/Compressive Strain = change in L / original L Shear Strain = distance of shear/original length
Hooke's Law Stress and strain are proportional Stress = modulus * strain Young modulus for tensile/compressive (Y/E) Shear modulus for shear (S/G)
What does modulus depend on? Modulus is the constant of proportionality between stress and strain Changes with composition (stronger intermolecular bonds, mean greater modulus) and with type of stress (some objects are more resistant to one type of stress than another)
Flea flag deltaL = FL(0)/EA deltaL = FL(0)/AG
Elementary charge e=1.6*10^-19 C
Coulomb's Law F(e) = kq1q2/r^2
Coulomb's constant 9*10^9 Nm^2/C^2
Speed of light 3*10^3 m/s
Electric field kQ/r^2
Force on q by field E F = qE
Unit for electric field N/C or (V=Ed) V/m
Eletric potential kQ/r
Change in electrical potential energy delta(PE) = qdelta(electric potential) = qV
Movement of charges and voltage Positive charges move to lower voltage, and negative charges move to higher
Work done by gravitational field W(grav) = -delta(PE)grav
Work done by E field W(efield) = -delta(PE)electric deltaKE = -deltaPE
electron Volt (eV) KE gained by electron with V change of +1 1 eV = 1.6*10^-19J
Super position of electric potential possible? Yep. Just add them up and watch the sign.
Possibilities with electric potential and electric field Could have 0 EP but an electric field, or vice versa
E field inside conductor is always 0!!!
Current I=Q/t
Resistance R= V/I
Resistance using resistivity R=pL/A p = resistivity
Resistivity (definition) Intrinsic resistance
Units for resistance V/amp or ohm 1 V/amp = 1 ohm
Resistivity slightly increases with increasing temp, but assume constant unless otherwise told
Ohm's Law V=IR
Adding resistors in series Add them
Adding resistors in parallel product/sum *warning* have to do it two at a time 1/R(t) = 1/R1 + 1/R2
I and V for series resistors I is constant, V is not
I and V for parallel resistors V is constant, I is not
Kirchoff's laws Voltage drop across resistors (parallel ones only count once) adds up to battery voltage Currents entering parallel systems equal the sum of the currents passing through the individual resistors
Power dissipated by resistor P= I^2R or P=IV
Power (circuit stuff) Energy = Power * Time
Unit for current C/s or amp
Units for newton kg*m/s^2s
Unit for voltage J/C
Effective emf in the presence of another battery the true voltage = V(boss battery) - V (low battery)
Batteries with internal resistance Box will be drawn around battery and its internal resistor sometimes Terminal voltage < e Terminal voltage = e - IR is battery supplies voltage Terminal voltage = e + Ir if that battery is charging
Charge on a capacitor Q=CV C is the capacitance
Capacitance of parallel plate capacitor C=k*e0*A/d K is dielectric constant (1 for air) e is permittivity of free space
Units for capacitance C/V or farad (F)
Permitivity of free space e0 = 1/(4pik0) = 8.85*10^-12 F/m
Ed's formula V=Ed
Electrical PE PE = (1/2)QV = (1/2)CV^2 = (1/2)Q^2/C
Capacitor charged, disconnected, dielectric added Q is constant V decreases PE decreases E decreases dipoles in dielectric decrease E and PE. E loss stored in dipoles, also cause dielectric to be sucked in when first inserted and also heat E induced by charges on surface of dielectric = -1/E
Capacitor charged, remains connected, dielectric added V constant Q increased PE increased E same Battery transfers extra charge to keep V constant
Dielectric breakdown E field exceeds max E for capacitor (V increases). Dieletric or air becomes ionized and form route for e- Adding dielec tried to prevent this from happening by allowing capacitor to hold more charge, thus, more PE without V increase. Dielec strength.
million 10^6
Dielectric strength Dielectric strength = E max
Adding parallel and series capacitors Opposite as resistors
What alternates in AC voltage and current
RMS voltage and current V(rms)=Vmax/sqrt2 I(rms) = Imax/sqrt2
Magnetic field vs electric field Magnetic field created by moving charges, and only exerts force on a moving charge "B" is magnetic field
Force of magnetic field F(B) = !q!vBsin0 0 is angle between v and B
Units for B N/(Am) or tesla (T)
Direction of Fb Always perpendicular to both v and B
Right hand rule for magnetic force fingers are B, thumb is v. Right hand for positive charge. Fb is on palm side
Do magnetic forces do work? why? No! because perpendicular to the velocity deltaKE=W, but KE doesn't change by magnetic force so....
period time per cycle
What determines the cyclotron period cyclotron period (T) is the time it takes for one evolution. It does NOT depend on r or v (how fast or size of circle). Depends only on mass and charge of particle and size of magnetic field
Lorentz force Total electromagnetic force. F by e field and F by m field
Magnetic field and I and r B proportional to I/r
How does the magnetic field look inside a solenoid Straight
Formula for magnetic field in solenoid B is proportional to I(N/L) N is number of turns per L
N and S poles of magnet convention Magnetic field exits through N and enters through S
Magnet and earth N pole of magnet aligns NEAR the S pole of earth. Earth has a non-uniform magnetic field
Hooke's law for simple harmonics F=-xk
Elastic PE PE(elastic) = (1/2)kx^2
v(max) A sqrt(k/m) A = x
Frequency (Concept) Number of cycles per second. 1 cycle/second is 1 hertz (Hz)
Period (equation) T= 1/T = 2pi*sqrt(m/k) T = 2pi*sqrt(l/g) l is legnth of pendulum
Frequecy (equation) f= (1/2pi)sqrt(k/m) f=(1/2pi)sqrt(g/l) Remember FK and TM
T/F frequency and period for simple harmonics depends on the amplitude False!!
Restoring force for pendulum Approximated for small angles F(restoring) = mg0 0 in rads!
Transverse waves Wave propagates in a direction perpendicular to the direction that the medium is vibrating
Wave equation v=(wavelength)(freq) v speed A wavelength f frequency
speed of wave for transverse rope waves v=sqrt(tension/linear density) Linear density of a rope is its mass/L
Frequency and period for pendulum is independent of its _____ mass
degree to radians conversion 180 degrees = pi
Two rules for waves 1. Speed of a wave depends on type of wave and medium, not by its frequency (exception is disperson) 2. Wave speed changes when it passes nother medium but frequency stays the same
What determines the amplitude of a wave How much energy we put into it. Doesn't depend on f, wavelength or v
Wavelength of a standing wave Distance between two nodes is 1/2wavelength
Standing wave wavelength for two fixed ends wavelength = (2L)/n = wavelength(fundamental)/n n is harmonic number
Standing wave frequency for two fixed ends F(n)=(nv)/2L F(n) = nF(fundamental)
Longitudinal wave Motion of the medium is parallel to direction of the wave traveling. Example - sound wave.
Sound waves Regions of compresion (high pressure) with regions of rarefractions (low pressure)
Traveling of sound waves depends on.... medium's resistance to compression and its density. The greater the resistance to compression, the faster the suond travels through it and the greater the medium density the slower it travels.
Standing sound waves in tube If both ends of tube are open, then they are both pressure nodes and the rules for transverse standing waves holds If one end closed, it is antinode
Standing waves with antinode Transverse wave tied lose at one end or long waves with one closed end. Antinode. wavelength(n) = 4L/n and F(n)=nv/4L n is an odd number
Beat frequency F(beat) = !F1-F2! Will have two frequencies possible unless you are given more info
Intensity vs intensity level Intensity: E it transmits per second (Power)per unit area Intensity level is based on intensity and the lowest intensity we can hear (I0)
Intensity units W/m^2 (power/area)
Intensity (sound) level B= 10*logbase10 of I/I0 Multiply I by 10 = add 10 to B Divide I by 10 = subtract 10 to B
Intensity and r r is distance from source Intensity is proportional to 1/r^2 and to amplitude^2
Droppler's effect As a source and detector move towards each other, the compressions reach the detector faster making it seem like v is faster. Since v=Af, we think f has increased and so we hear higher pitch. When they move away we perceive lower f.
Droppler's effect equation f(d) = f(s)* (v +/- v(d))/ (v -/+ v(s)) top sign for towards
Redshift droppler's effect with light. Stars moving away seem to turn red because we perceive their f of light as incresing
Electronic waves Oscillating electric charge generates electromagnetic wave (composed of oscillating electric and magnetic fields that oscillate at the same f as the electric charge that made them) E and B field oscilate in phase and perpendicular dont require mediu
Speed of light (c) Light travels in a vacuum at constant speed 3*10^8 m/s
light spectrum ROYGBV (700 nm to 400 nm)
Photon E E=hf=h(c/wavelength)
E for waves and particles(photons) E for waves is proportional to squared amplitude E for particles(photos) is proportional to frequency
Law of reflection angle of reflection is the same as the angle of incidence in reference to vertical line
Index of refraction n = c/v v is the speed of light in that medium vaccum is n = 1. air is close enough so we use n = 1 also
Snell's law (Law of refraction) n1sin01 = n2sin02 if n2>n1 then 02<01 0 is measuredtowards normal.
when does total internal reflection occur When a ray's angle of incidence exceeds a critical angle and all its energy is then reflected back into the original medium (no refraction)
Crtical angle for total internal refraction sin0(crit)=n2/n1 only when n1>n2
Diffraction Redistribution of wave's intensity when it reaches an obstruction.
Plane-polarized light E field components are all in a single plane. Waves in a beam of light are NOT vibrating in all planes but restriction to one.
Dispersion different wavelengths are bent more or less, because different f causes slightly different speeds traveling through same medium (exception to big rule 1). Doesn't apply to vacuum. Generally higher f means lower speed
Plane mirror Image is upright, not inverted
Spherical mirror convex and concave
Reflection of concave mirror Light reflected cross focal point F, halfway through the center of curvature (c) which is where the center of the circle is
Focal lenth for concave mirror f=(1/2)r
Reflection of convex mirror Light is reflected away from the imaginary focal point behind the mirror
Real vs virtual image Real if light actually focus at the position of the image virtual if light doesnt actually focus at the apparent location of the image positive i = real negative i = virtual
Mirror and lens equation 1/o + 1/i = 1/f o is distance from object to mirror (always +) f is focal length i is the image's distance from mirror If f and i are both + if on same side of observer. Mirror same side, lense oppposite side.
Magnification equation m= -i/o m is magnification factor. positive then upright, negative then inverted
Real images are ___ while virtual ones are _____ inverted, upright
Lenses form an image of an object by _____ light refracting light
focal length of mirror converging has positive f length, diverging has negative
A concave mirror is divering or converging? Converging. A convex mirror is a diverging
A convex lense is diverging or converging Converging. A concave mirror is diverging.
Focal length for a converging this is? Positive. DIEverging would be negative focal length.
Little lines on the mirror indicate The backside
Real or virtual image for diverging lenses/mirror? Virtual onlY!!!
Image is where the rays or their tracebacks converge
Power and focal length shorter focal length, refracts at larger angle, has more power P = 1/f unit is diopter(D) when f is in meters. Keep signs of F in mind! P = P1 +P2
Correction for presbyopia is the same as correction for farsightedness because they cant focus an image.
Upright image must have a ____ magnitude positive
Dot product of vectors Always a scalar dot product = !v!!w!cos0 !v! = magnitude of v Ex. W = F(dot)d = Fdcos0
Cross product of vectors cross product = !v!!w!sin0 Direction is always perpendicular to w and v Ex. F(b) = qv X B = qvBsin0
Area under a graph of velocity vs. time is.... distance NOT displacement
Maximum height for projectile motion 1/8gt^2
Air resistance and projectile motion (what I learned from EK) Air resistance increases with SA, air density, and velocity. Heavier m, longer TOF Heavy but spherical objects face very small air resistance (you can treat as no air resistance).
Four forces in nature3 Strong nuclear, weak nuclear, gravitational, and electromagnetic
What happens to k when you cut a spring in half? It doubles!!!
What happens to k when two identical springs are placed in parallel It doubles!!!
Anticipation (in relation to genetic diseases) Anticipation is when future generations show earlier onset of the disease (Ex. Huntington with the increase number of repeats)
force of friction relation to KE and W Fd = KE but is NOT equal to W
Block hanging from rope, couldn't make mgh = work because... Gravity isn't the only force acting on it
The most difficult object to stop is the one with the most ___ Momentum
The most difficult object to change velocity is the one with most ____ Inertia
Created by: valen1014