MCAT Physics

STP

1 atm 273k = 0C

1 mole of gas

22.4L

speed of light

3*10^8 m/s

Planck's constant

6.62*10^-34 J/s

controls

A is correct. A positive control is a control group that is not exposed to the experimental treatment but that is exposed to some other treatment that is known to produce the expected effect. The scientists wished to test the effect of the analogs on enzyme activity. Using a known inhibitor is an example of comparing the expected effects of this inhibitor to those of the analog treatment. Thus, it is a positive control. B: A negative control group is a control group that is not exposed to the experimental treatment or to any other treatment that is expected to have an effect. C: In randomized controls, the groups that receive different experimental treatments are determined randomly. There was nothing random about this selection. D: A false negative is when a test result appears negative when it should have been positive. An example of a false negative would be if a particular test of a known ADAMTS inhibitor returns a result that shows no change in enzyme activity.

what is the difference between the pressure for liquids and gases, in relation to density?

Hydrostatic pressure for liquids is linear because as depth changes, the density of the liquid remains constant. Gases, however, have densities that change according to the forces applied to them. Gases are compressible, while liquids and solids are not.

alkane formula

C(n)H(2n+2)

air bubbled through distilled water

CO2 undergoes hydrolysis in liquid water to produce HCO3- weak acid has a pH less than water

1/2 life

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wavelength of photons

E = hc/wavelength

downward pulling force

Force(net) = mgsin(theta) - (static frictional force)mgcos(theta) Force = Ma, so masses will cancel mgsin(theta)

Indicators desired range

Indicators function in acid-base titrations to identify, via color change or a similar mechanism, that an expected pH, and thus the titration endpoint, has been reached. In order to function in this way, an indicator must undergo a color change near the desired pH. This typically occurs because of a reversible change in the protonation state of the indicator. It is desirable then that the pKa of a chosen indicator be within ±1 unit of the target pH. For the titrations performed in the study of acetic acid, a weak acid, and sodium hydroxide, a strong base, the endpoint of the titration will occur at a pH greater than 7. Of the possible pKa values given as answer choices, only D could function well as an indicator for a pH in this range.

velocity of an object dropped

KE = PE 1/2 mass * velocity (squared) = mass * gravity * height

Henderson-Hasselbach

Ka + Kb = 10^-14 The equivalence point on the graph is where all of the starting solution (usually an acid) has been neutralized by the titrant (usually a base). It can be calculated precisely by finding the second derivative of the titration curve and computing the points of inflection (where the graph changes concavity); however, in most cases, simple visual inspection of the curve will suffice. In the curve given to the right, both equivalence points are visible, after roughly 15 and 30 mL of NaOH solution has been titrated into the oxalic acid solution. To calculate the acid dissociation constant (pKa), one must find the volume at the half-equivalence point, that is where half the amount of titrant has been added to form the next compound (here, sodium hydrogen oxalate, then disodium oxalate). Halfway between each equivalence point, at 7.5 mL and 22.5 mL, the pH observed was about 1.5 and 4, giving the pKa. In monoprotic acids, the point halfway between the beginning of the curve (before any titrant has been added) and the equivalence point is significant: at that point, the concentrations of the two species (the acid and conjugate base) are equal. Therefore, the Henderson-Hasselbalch equation can be solved in this manner: pH=pKa (monoprotic) Therefore, one can easily find the pKa of the monoprotic acid by finding the pH of the point halfway between the beginning of the curve and the equivalence point, and solving the simplified equation. In the case of the sample curve, the Ka would be approximately 1.78×10−5 from visual inspection (the actual Ka2 is 1.7×10−5) **Why ten to the -5?

electric power

P = IV

hydrostatic pressure

P is absolute pressure Po is pressure at the surface p is density of the fluid g is acceleration due to gravity z is depth

elastic potential energy

SI unit = joules

gravitational potential energy

SI unit = joules

capacitance - what are the units?

SU unit = faraday

substrate analog

Substrate analogs (substrate state analogues), are chemical compounds with a chemical structure that resemble the substrate molecule in an enzyme-catalyzed chemical reaction. Substrate analogs can act as competitive inhibitors of an enzymatic reaction

pI

The isoelectronic point or isoionic point is the pH at which the amino acid does not migrate in an electric field. This means it is the pH at which the amino acid is neutral, i.e. the zwitterion form is dominant. A table of pKa and pI values can be found on the next page. The pI is given by the average of the pKas that involve the zwitterion, i.e. that give the boundaries to its existence. 1/2 (pKa1 + pKa2)

object rolling down a ramp

U = mgh

work equation (for kinematics)

W = fdcos (theta)

binding energy

energy that holds the protons and neutrons together in the nucleus, defined by the equations E=mc2, where m is mass defect and c is the speed of light in a vacuum

Newton's second law

f = ma

archimedes principle

a body that is fully or partially immersed in a liquid will be buoyed upwards by a force that is equal to the weight of the liquid displaced by the body F(buoy) = density(fluid)*volume(submerged)*gravity

Newton's third law

action and reaction

Mechanical advantage

advantage compared to not lifting straight up hypotenuse/height = MA **Think about right triangle rules

amide, amine, imine, thirster, thioketone

amide: carboxyl group, alpha nitrogen amine: nitrogen attached to 2 R groups mine: nitrogen in the double bond thioester: sulfur with two R groups thiokeytone: sulfur in a double bond, 2 R groups attached to the Carbon

heat of transformation

amount of heat required to change the phase of a substance

electric potential energy

amount of work required to bring a test charge q from a point within the electric field of some source charge Q U = qV. V = kQ/r

logarithm

base 10 base 2.72 = ln

Beta minus

negative, so positrons are attracted to it

agonist antagonist

causes an action stops an action

For mirrors, are the images in front of a concave mirror converging/diverging? real/virtual? for concave, if the object is placed at the focal point? are the images in front of a convex mirror real or virtual?

concave = real, converging, light converges in front of mirror, parallel rays converge at the focal point, if the object is within the focal point, it's a virtual image. IF object at the focal point, then there is no image concave mirror with a positive focal length, convex = light is virtual and appears in front while a diverging mirror is convex mirror with a negative focal length. Diverging mirrors always produce virtual images

equipotential lines

concentric circles emanating from a source charge that cross its electric field liens perpendicularly. No work is required for a test change to travel along the circumference of an equipotential line because the potential at every point along that line is the same

Bernoulli's equation

conversation of energy in fluid flow for a given depth, linear flow speed and pressure are inversely related

partial pressure

convert pressure to desired unit 1 atm = 760 mmHg = 760 torr = 100,000 Pa Then, look for percentage composition of that gas and multiply

wavelength

crest to crest, trough to trough

exponential decay

decrease in the amount of a substance N at an exponential rate y(t) = a × ekt (k=-wavelength)

focal length

distance between the focal point and the mirror or lens. spherical mirrors = focal length = 1/2r

conservative force

doesn't dissipate gravity electrostatic forces elastic forces

current -what kind of charge is this? what does current depend on -besides resistance?

flow of charge/time potential difference (voltage) Current is denoted I delta q/time (theoretical positive charge)

second law of thermodynamics

for any process, the entropy of the universe either increases (for irreversible processes) or remains constant (for reversible processes)

torque

force creating rotation about an axis; measured as the lever arm (the distance between the fulcrum and the applied force) times the magnitude of the force times the sine of the angle between them

nonconservative force

force that dissipates

pressure

force/area

gamma decay

gamma particles = high-energy photons

half-life

half life = ln2/decay constant

alpha decay

helium emitted

sigmoidal curves

increased concentration of binding substance on a molecule increases binding capacity for the substance

viscosity

resistance to flow, denoted by n

dielectric

insulating material placed in between the two plates of a capacitor, increases capacitance

First Law of Thermodynamics

internal energy of a system is equal to the heat transferred into a system minus the work done by the system delta U = Q -W

kinetic energy

k = 1/2mv(squared) unit: joules

sound level

loudness measured in decibels I is intensity of the sound I knot is the reference intensity of 10(-12) W/m(2)

magnification

m= -I/o

scalar

magnitude but no direction

density

mass/volume specific gravity

mass

measure object's inertia

kcat/Km

measure of the efficiency of an enzyme - Vmax decided by the total turnover number, this is the slowest/rate determining step Kcat = turnover molecular number (units = 1/sec)

Ideal gases

more ideal the higher the temps, but colder air can hold less water

dispersion/equation for n in light refraction (in terms of wavelength)

n = c/f(wavelength)

snell's law

n1sin1 = n2sin2

translational equilibrium

no net movement

frequency

number of cycles per second 1Hz = 1 cycle per second

conservation of mechanical energy

only conservative forces act on an object and work is done, energy is conserved delta E = delta U = delta K = 0

weak acids

pH = -log [H+] [H+] = 10 raised to the -pH

percent dissociation

percent original acid concentration that has dissociated

normal force

perpendicular component of the force caused when two surfaces push against each other, denoted by N

photoelectric effect

phenomenon observed when light of a certain frequency causes a metal to emit electrons. W = work function calculates the residual kinetic energy of an electron emitted by a metal K = hf - W

gauge pressure

pressure above and beyond atmospheric pressure. h = depth

plane mirrow

produces virtual image that appears to be the same distance behind the mirror as the object is in front of the mirror

resistivity

property of a conductor used to measure its resistance in the equation r = resistivity*length/area r=resistance area=cross-sectional area

electromagnetic spectrum

radio microwave infrared ROYGBIV ultraviolet Xray gamma

index of refraction

ratio of the speed of light in a vacuum to the speed of light through a medium

laminar flow

smoothest type of liquid flow through a tube wherein thin layers of liquid slide over one another. occurs as long as the linear flow speed remains below a critical speed.

wave speed

speed of a wave

work-energy theorem

states that the net work performed on an object is related to its change in energy.

homotropic/allosteric regulation

substrate for the enzyme as well as regulator for the enzyme

kirchoff's loop rule

sum of the voltage sources in a circuit loop is equal to the sum of voltage drops along that leap

electric potential

the amount of electric potential energy per unit charge; the work required to bring a positive test charge from infinity to within an electric field of another positive source charge, Q, divided by that test charge's magnitude. V = kQ/r

total internal reflection

the condition in which the incident angle of light traveling from a medium with a high n to a medium with a low n is greater than the critical angle theta. This results in all of the light being reflected and none of it being refracted.

mass defect

the difference between an atom's atomic mass and the sum of masses of its protons and neutrons

potential difference

the difference in the electrical potential between two points in a an electric field, also called voltage

coulombs law

the law describing the electrostatic force that exists between two charges

continuity equation

the mass flow rate of fluid must remain constant from one cross-section of a tube to another a1v1 = a2v2 relates much more to compressibility than viscosity

0th law of thermodynamics

two objects that are in thermal equilibrium with a third object are also in thermal equilibrium with each other

force

unit = Newton

acceleration

vector describing a change in velocity over time a= change in velocity/time

Ohm's Law

voltage = current*resistance

pascal's principle

when a pressure is applied to one point of an enclosed fluid, that pressure is transmitted in equal magnitude to all points within the fluid and to the walls of its container. This principle forms thesis of the hydraulic lift

interference

when superimposed waves are in phase, their amplitudes add (constructive interference). When superimposed light waves are out of phase, their amplitudes subtract (destructive interference)

power in terms of work

work/time SI unit = watt