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# MCAT Physics (VL)

Question | Answer |
---|---|

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