Chem/Phys Flashcards
How is a scalar calculated from the product of two vectors?
Dot product ( [A] x [B] x cos theta )
How is a vector calculated from the product of two vectors?
Cross product ( [A] x [B] x sin theta )
When calculating frictional forces, how is directionality assigned?
The direction of friction always opposes movement, so once the instantaneous velocity/net force vector is known, the frictional force must be in the opposite direction
When no force is being applied, the velocity must be:
Constant (no acceleration)
How do the forces acting in free fall and projectile motion differ?
Gravity is the only force present in both free fall and projectile motion
What is the difference between rotational equilbrium and translational equilibrium?
Rotational equilibrium occurs in the absence of net torque acting on an object, translational equilibrium occurs in the absence of any net forces acting on an object
What are conservative forces, and how do they impact mechanical energy? Does the path taken matter? What are some examples?
Conservative forces = total mechanical energy does not change, path taken does not matter, examples = gravity and electrostatic forces
What are nonconservative forces, and how do they impact mechanical energy? Does the path taken matter? What are some examples?
Nonconservative forces = total mechanical energy does change, path taken does matter, examples = friction and air resistance
What are three ways of calculating work?
W = Fd cos theta, W = P DeltaV, W = DeltaK
As the length of an inclined plane increases, what happens to the force required to move an object the same displacement?
The force required decreases
What accounts for the difference between work input and work output in a system that operates at less than 100% efficiency?
Decrease in work output is due to nonconservative or external forces that generate/dissipate energy
What are the six simple machines?
Inclined plane, wedge, wheel and axle, lever, pulley, and screw
A 1000 kg rocket ship, traveling at 100 m/s, is acted upon by an average force of 20 kN applied in the direction of its motion for 8 seconds. What is the change in velocity of the rocket?
F = ma -> a = F/m -> a ( or change in V) = (20 x 10^3) (8) / (1000 kg) = 160 m/s
A car is traveling at 40 km/hr and the driver puts on the brakes, bringing the car to rest in a time of 6 seconds. What is the magnitude of the average acceleration of the car?
USE EQUATION A = delta V/t -> (40 km/hr) (600 seconds/1 hr) = 24,000 km/hr^2
If an elevator is moving upward at speed of 5 m/s after an initial period of acceleration, what is the relationship between the maximum tension of the cable and the maximum weight of the elevator?
The tension is greater than the maximum weight
If one object is thrown vertically downward at 5 m/s and another object is thrown vertically upward with a speed of 10 m/s, which object undergoes a greater change in speed in 2 seconds?
The first object has a greater change in speed
A firefighter jumps horizontally from a burning building with an initial speed of 1.5 m/s. At what time is the angle between his velocity and acceleration vectors the greatest?
The instant he jumps
A 10 kg wagon rests on a frictionless inclined plane. The plane makes an angle of 30 degrees with the horizontal. Approximately how large is the force required to keep the wagon from sliding down the plane?
mg sin theta = (10) (9.8) sin 30 = 49 N
A 20 kg wagon is released from rest from the top of a 15 m long lane, which is angled at 30 degrees with the horizontal. Assuming that there is friction between the ramp and the wagon, how is this frictional force affected if the angle of the incline is increased?
As theta increases, cos theta decreases which decreases the frictional and normal forces)
A BASE jumper runs off a cliff with a speed of 3 m/s. Which of the following is closest to his speed after 0.5 seconds?
V = V0 + at -> V = (-9.8) (0.5) = -4.9 -> Pythagorean theorem (sqrt ((3)^2 + (-4.9)^2)) = sqrt (34) ~ 6 m/s
A 2 kg rock is shot up vertically at the same time that a 0.5 kg ball is projected horizontally. If both start from the same height:
The ball will reach the ground first
What is a true statement about movement on a plane with friction?
More force is needed to accelerate a stationary object than an identical moving object
What is the value of tension in each rope in a pulley system if the mass of the object is 10 kg and the object is accelerating upwards at 2 m/s^2?
2T - mg = ma -> 2T = m (g + a) -> T = 10 (10+2) / 2 = 60 N
A massless spring initially compressed by a displacement of two centimeters is now compressed by four centimeters. How has the potential energy of this system changed?
The potential energy has quadrupled (elastic potential energy = 1/2 kx ^2, 2^2 = 4)
A parachutist jumps from a plane. Beginning at the point when she reaches terminal velocity (constant velocity during freefall), what are some true statements?
The jumper is in translational equilibrium, and there is an equal amount of work being done by gravity and air resistance
A consumer is comparing two new cars. Car A exerts 250 horsepower, while Car B exerts 300 horsepower. The consumer is most concerned about the peak velocity that the car can reach. If nonconservative forces can be ignored, which of the following statements is true?
Car A and Car B both have unlimited velocities
What is the transition state theory?
Forming a high-energy activated complex that can then proceed forward or backward, forming the products or reverting to the reactants
What is the collision theory?
The energy and orientation of reactants, and considers each potential reaction to be “all-or-nothing”
In a certain equilibrium process, the activation energy of the forward reaction is greater than the activation energy of the reverse reaction. This reaction is:
Nonspontaneous
What is the equation for Q?
Q = concentration of products / concentration of reactants
If pH is increased in a chemical reaction:
The reaction shifts towards H+ because the concentration of H+ decreases
What are kinetic products?
Kinetic products are favored at low temperatures with low heat transfer
What are thermodynamic products?
Thermodynamic products are favored at high temperatures with high heat transfer
On a reaction coordinate diagram, how do kinetic pathways compare to thermodynamic pathways?
Kinetic pathways require a smaller gain in free energy to reach the transition state, have a higher free energy of the products, and a smaller difference in free energy between the transition state and the products
A reaction if found to stop just before all reactants are converted to products. Which of the following could be true about this reaction?
The reaction is reversible, and the forward rate is equal to the reverse rate
What is the value of K that is used for gases?
Kp
What are a few statements about equilibrium reactions?
As the concentration of the products increases, the concentrations of reactants decreases; the equilibrium constant is altered by changes in temperature
What is the maximum distance that two objects can be from one another and still adhere to the zeroth law of thermodynamics?
There is no maximum distance
What is the most accurate measurement method for temperature?
There is none; Celsius and Kelvin are equally as good
What are some examples of state functions?
Pressure, density, temperature, volume, enthalpy, internal energy, Gibbs free energy, entropy
What are some examples of path functions?
Heat and work
What is the relationship between internal energy, work, and heat?
Internal energy = heat - work
What is conduction?
Heat exchange by direct molecular interactions
What is convection?
Heat exchange by fluid movement
What is radiation?
Heat exchange by electromagnetic waves, and does not depend on matter
Where is work on a P-V graph?
The area under the curve
What is entropy in macroscopic and statistical terms?
Macroscopic = tendency toward disorder, statistical = measure of the spontaneous dispersal of energy at a specific temperature
What is the relationship between the entropy of a system and its surroundings for any thermodynamic process?
Will never decrease (will either remain constant or increase)
What is the relationship between Celsius and Kelvin?
The kelvin unit and Celsius degree are the same size
What occurs when heat is transferred from the Sun to the Earth?
Radiation
What occurs when a metal spoon heats up when placed in a pot of hot soup?
Conduction
What occurs when a rising plume of smoke emerges from a fire?
Convection
A 20 m steel rod at 10 degrees C is dangling from the edge of a building and is 2.5 cm from the ground. If the rod is heated to 110 degrees Celsius, will the rod touch th ground?
No because it expands by 2.2 cm (delta L = alpha * L * delta T) - beta = 3*alpha
What is the final temperature of a 3 kg wrought iron fireplace tool that is left in front of an electric heater, absorbing heat energy at a rate of 100 W for 10 minutes? Assume the pendant is initially at 20 degrees C, and that the specific heat of wrought iron is 500 J / kg * K - what equations do you use?
E = P*T and q = mcdeltaT
How much heat is required to completely melt 500 g gold earrings, given that their initial temperature is 25 degrees C? (MP of gold is 1064 degrees C, heat of fusion = 6.37 x 10^4 J/kg, specific heat = 126 J / kg*k) - which equations do you use?
E = P * t , q = mcdeltaT
In an adiabatic compression process, the internal energy of the gas:
Increases because the work done on the gas is positive
The entropy of a system can:
Decrease when the entropy of the surroundings increases by at least as much (no net decrease)
If two substances have the same freezing and boiling points, and solid samples of both substances are heated in the exact same way, substance A boils before substance B. Why?
Substance B has a higher specific heat, heat of vaporization, and heat of fusion
In experiment A, a student mixes ink with water and notices that the two liquids mix evenly. In experiment B, the student mixes oil with water; in this case, the liquids separate into two different layers. The entropy change is:
Positive in experiment A and zero in experiment B
What is gauge pressure?
Gauge pressure is equal to the pressure exerted by a column of fluid plus the ambient pressure above the fluid, minus atmospheric pressure. When atmospheric pressure is the only pressure above the fluid column, then gauge pressure equals the fluid pressure
How are weight and density related?
Weight is density * volume and acceleration due to gravity
To which side of a hydraulic lift would the operator usually apply a force - the side with the larger or smaller cross-sectional area?
Smaller cross-sectional area because pressure will be the same on both sides of the lift, so a smaller force can be applied on the smaller surface area to generate the desired pressure
What is dynamic pressure?
The pressure associated with flow, and is represented by 1/2 pv^2
What is static pressure?
The pressure associated with position, is sacrificed for dynamic pressure during flow
What is a pilot tube?
A device that measures static pressure during flow to calculate speed
What is viscosity?
A measure of the resistance of a liquid to flow
What is laminar flow?
Flow in which there are no eddies and in which streamlines are roughly parallel to each other
What is turbulence?
The presence of backflow or current eddies
What is the continuity equation?
Describes the relationship of flow and cross-sectional area in a tube (A1V1 = A2V2)
What is Bernoulli’s equation?
States that 1) points 1 and 2 lie on a streamline, 2) the fluid has constant density, 3) the flow is steady, and 4) there is no friction; (p1 (pressure energy) + 1/2pv1^2 (kinetic energy) + pgh1 (potential energy) = p2 + 1/2pv2^2 + pgh2)
What is the Venturi effect?
Q = AV; flow rate stays the same and surface area decreases = velocity must increase
What equation can be applied to the circulatory system?
Poiseulle’s Law (Q = pi * pressure * r^4 / 8 * viscosity * length of tubing)
What happens to air as it exits the body?
Resistance increases
How does the flow in the venae cavae relate to flow in the main pulmonary artery?
The flow should be equal, but the flow is a little less in the venae cavae because some of the blood entering the heart is from cardiac circulation
If the density of object A is one third of object B, and the gauge pressure of object A is 3 atm, what is the gauge pressure of object B?
3 atm (gauge pressure depends on density of FLUID) - gauge pressure (of fluid) = total pressure - atmospheric pressure
An anchor made of iron weighs 833 N on the deck of the ship. If the anchor is now suspended in seawater by a massless chain, what is the tension in the chain?
Tension = Fg - Fbuoy = 833 N - 109 N = 724 N
Water flows from a pipe of diameter 0.15 m into one of diameter 0.2 m. If the speed in the 0.15 m pipe is 8 m/s, what is the speed in the 0.2 m pipe? - what equation should you use?
V1A1 = V2A2 -> 8 (0.15/0.20) ^ 2 = 4.5 m/s
If water is allowed to flow through the pipe to the right, in which of the vertical pipes will the water level be lowest?
Pipe 2 (smallest horizontal diameter)
Which of the following data sets is sufficient to determine the linear speed through an area of a rigid pipe?
The radius, pressure gradient, viscosity, and length of the pipe (Poiseuille’s Law - pipr^4 / 8viscositylength of tubing)
A large cylinder is filled with equal volumes of two immiscible fluids. A balloon is submerged in the first fluid; the gauge pressure in the balloon at the deepst point in the first fluid is found to be 3 atm. Next, the balloon is lowered all the way to the bottom of the second fluid, where the hydrostatic pressure in the balloon reads 8 atm. What is the ratio of the gauge pressure accounted for by the first fluid to the gauge pressure accounted for by the second fluid?
3:04
What is the relationship between Bernoulli’s equation and flight?
The speed of airflow is greater over the curved top of the wing, resulting in less pressure on the top of the wing and the production of a net upward force on the wing, in turn resulting in flight
What are the values of isothermal, adiabatic, isobaric, and isovolumetric?
Isothermal = delta U = 0, Q = W; Adiabatic = Q = 0, delta U = -W; Isobaric = line appears flat in a P-V graph; Isovolumetric = W = 0, delta U = Q
What is the triple point?
The specific combination of temperature and pressure at which all three phases are in equilibrium
What is the critical point?
The temperature and pressure above which the liquid and gas phases are indistinguishable and the heat of vaporization is zero
What is heat capacity?
Specific heat * mass
What is a coffee cup calorimeter?
Constant pressure calorimeter - As the reaction proceeds, the temperature of the contents is measured to determine the heat of the reaction
What is a bomb calorimeter?
Heats of certain reactions (like combustion) can be measured indirectly by assessing temperature change in a water bath around the reaction vessel (CONSTANT VOLUME CALORIMETER)
What is a calorie?
1 cal/ g*K
What is the difference between endothermic and exothermic reactions?
Endothermic reactions involve an increase in heat content of a system from the surroundings, while exothermic reactions involve a release of heat content from a system
Can entropy of the universe decrease?
No
What is sublimation?
Solid -> gas
What is deposition?
Gas -> solid
What is the equation for Gibbs free energy?
Delta G = Delta H - T*Delta S
What is the shape of adiabatic on a P-V graph?
Hyperbolic
What is the equation for change in Gibbs free energy?
Delta G = Delta Gprime + RTlnQ
Explosions are necessarily characterized by:
Negative Delta G
Name some characteristics that make the gas phase unique.
Gases are compressible fluids with rapid molecular motion, large intermolecular distances, and weak intermolecular forces
How would atmospheric pressure change by altitude?
Atmospheric pressure is lower at higher altitude, hydrostatic and atmospheric pressures are present at lower altitudes
What is STP?
T = 273 K (0 degrees C), P = 1 atm
What are standard conditions?
T = 298 K (25 degrees C), P = 1 atm, concentration = 1 M
How do I find density from the PV = nRT equation?
Density = m/v = PM/RT
How can the concentration of carbon dioxide in sodas or other carbonated beverages be so much higher than that of atmospheric carbon dioxide?
High pressures of carbon dioxide gas are forced on top of the liquid in sodas, increasing its concentration in the liquid
What are some assumptions of the kinetic molecular theory?
Negligible volume of gas particles, no intermolecular forces, random motion, elastic collisions, proportionality between absolute temperature and energy
What is the root mean square speed equation?
Urms = sqrt (3RT/M)
What equation should you use to determine average speed?
r1/r2 = sqrt (M2/M1)
Why would you smell a rotten egg odor (hydrogen sulfide) before wintergreen (methyl salicylate)?
Since they are at the same temperature, the gases that is the lightest travels the fastest
In what ways do real gases differ from ideal gases?
Real gases deviate from ideal gases at high pressure (low volume) and low temperature
Which gas will exert a higher pressure under the same, nonideal conditions: methane or chrloromethane?
The real pressure of methane will be higher (closer to ideal), value of a is smaller for methane
If methane and isobutane are placed in the same size container under the same conditions, which will exert the higher pressure?
Since the b value is higher for isobutane, it would make the “v-nb” value smaller, so the pressure for isobutane would have to increase
What is ideal gas behavior?
High temperature and low pressure
Ideal gases have:
Particles with no attractive forces between them
An 8.00 g sample of NH4NO3 is placed into an evacuated 10 L flask and heated to 227 degrees C. After the NH4NO3 completely decomposes, what is the approximate pressure in the flask?
1.23 atm - write out a balanced equation, convert to moles
How would speed of helium and bromine compare to each other on a graph?
Helium has a smaller molar mass than bromine, greater overall average speed
The gaseous state of matter is characterized by:
Gases are compressible and assume the volume of their containers
When placed one meter apart from each other, which will experience greater acceleration: one coulomb of electrons or one coulomb of protons?
One coulomb of electrons (same charge, less mass)
What are some examples of insulators and conductors?
Insulators = hair, glass, distilled water; Conductors = blood, copper, iron, sulfuric acid
How do distance and charge relate to electrostatic force?
Directly related to each charge, related to the distance by an inverse square relationship
How do distance and charge relate to electric field?
Unrelated to test charge, related to distance by an inverse square relationship
How does a change in electric potential energy from -4 J to -7 J reflect on the stability of the system?
More stable
Compare the relationship between electric potential energy and Coulomb’s law to the relationship between gravitational potential energy and the universal law of gravitation
Coulomb’s law (kq1q2 / r^2) = EPE (kq1q2 / r)* distance, Universal law of gravitation (Gm1m2/r^2) = GPE (mgh) * distance
By what factor would electric potential energy change if the magnitude of both charges were doubled and the distance between them was halved?
The EPE would be multiplied by a factor of 8
What is the difference between electric potential and voltage?
Electric potential = the ratio of a charge’s electric potential energy to the magnitude of the charge itself, Voltage = a measure of the change in electric potential between two point
How will a charge that is placed at a point of zero electric potential move relative to a source charge?
Will move in a way to minimize its potential energy, the charge may or may not move
What are the units of electric potential energy / electric potential?
EPE = Joules, EP / PD (voltage) = Volts
What are equipotential lines?
The sets of points within space at which the potential difference between any two points is zero, there is no voltage between two points on an equipotential line
What is an electric dipole?
The separation of charge within a molecule such that there is a permanent or temporary region of equal and opposite charges at a particular distance
Why is the electric potential at points along the perpendicular bisector of a dipole zero?
The perpendicular bisector of an electric dipole is an equipotential plane that is perpendicular to the axis of the dipole. As such, the equation V = kqd / r^2 cos theta is necessarily equal to 0 because cos 90 = 0
What is the behavior of an electric dipole when exposed to an external electric field?
A dipole will rotate within an external electric field such that its dipole moment aligns with the field
How do you create an electric field?
Charge
How do you create a magnetic field?
Charge that is moving
How do you create a magnetic force?
An external electric field acting on a charge moving any direction except parallel or antiparallel to the external field
Two parallel conducting plates are separated by a distance d. One plate carries a chare +Q and the other carries a charge -Q. The voltage between the plates is 12 V. If a +2uC charge is released from rest at the positive plate, how much kinetic energy does it have when it reaches the negative plate?
W = delta U = Q * delta V = (2 x 10^-6 C) (-12 V) = -2.4 x 10^-5 J
If the magnetic field a distance r away from a current-carrying wire is 10T, what will the net magnetic field at r if another wire is placed a distance of 2r from the original wire (with r in the middle) and has a current twice as strong flowing in the opposite direction?
30 T
Given an electric dipole, the electric potential is zero:
Anywhere on the perpendicular bisector of the dipole axis and at infinity
A certain 9 V battery is used as a power source to move a 2 C charge. How much work is done by the battery?
Delta V = Delta U / q = W / q (9 V * 2 C = 18 J)
A proton and an alpha particle repel each other with a force of F while they are 20 nm apart. If each particle combines with three electrons, what is the magnitude of the new force between them?
Force would still be F
A moving negative charge placed in an external magnetic field circulates counterclockwise in the plane of the paper. In which direction is the magnetic field pointing?
Out of the page
A dipole is placed in an electric field and is allowed to come to equilibrium. How would the dipole react if the direction of the electric field is suddenly reversed?
It experiences no rotational or linear movement
What is current?
The movement of positive charge through a conductive material over time, unit = amperes
What is voltage?
A potential difference between two points, unit = Volts
What is electromotive force (emf)?
The potential difference of the voltage source for a circuit, unit = Volts
What is conductivity?
The reciprocal of resistance, a measure of the permissiveness to current flow, unit = siemens
Which likely has a higher conductivity: 1 M glucose or 0.25 M NaCl?
0.25 M NaCl (is a salt, will increase the ion content of water)
In a circuit, the number of electrons entering a point and leaving that point are the same
True (Kirchhoff’s Junction Rule)
The sum of the voltage sources in a circuit is equal to the sum of the voltage drops in that circuit
FALSE
How does adding or removing a resistor change the total resistance of a circuit with resistors in series? In parallel?
Adding a resistors to resistors in series increases the resistance, decreases the resistance for resistors in parallel
How does power relate to current, voltage, and resistance?
P = IV = I^2R = V^2/R
A circuit is set up with three resistors. What proportion of the total current will travel through each resistor?
All of the circuit will go through the first resistor
After a voltage source has been taken away, how does the capacitor behave?
The capacitor discharges, providing a current in the opposite direction of the initial current
How does a dielectric material impact capacitance? Voltage? Charge?
Will always increase capacitance, will decrease voltage and keep charge constant if isolated, will keep voltage constant and increase charge if part of a circuit
How does adding or removing a capacitor change the total capacitance of a circuit with capacitors in series? In parallel?
Adding a capacitor in series decreases the total capacitance, removing one in series increases the total capacitance (opposite for parallel)
What physical qualities contribute to the capacitance of a capacitor?
Dielectric constant, distance, surface area
What is an ammeter?
Measures current, placed in series with point of interest, ideally zero resistance
What is a voltmeter?
Measures potential difference (voltage), placed parallel with circuit element of interest, ideally infinite resistance
What is an ohmmeter?
Measures resistance, placed at two points in series with circuit element of interest, ideally zero resistance
True or False: a voltmeter and an ammeter should not be placed in the same circuit
False, they can be used together
A voltaic cell provides a current of 0.5 A when in a circuit with a 3 ohms resistor. If the internal resistance of the cell is 0.1 ohms, what is the voltage across the terminals of the battery when there is no current flowing?
V = IR -> (0.5 A)(3 ohms) = 1.5 V; e = V + ir = 1.5 V + (0.5 A)(0.1 ohm) = 1.55 V
A transformer is a device that takes an input voltage and produces an output voltage that can either be larger or smaller than the input voltage, depending on the transformer design. Although the voltage is changed by the transformer, energy is not, so the input power equals the output power. A particular transporter produces an output voltage that is 300% of the input voltage. What is the ratio of the output current to the input current?
1:3 -> IoutVout = IinVin
How many moles of electrons pass through a circuit containing 100 V battery and a 2 ohm resistor over a period of 10 seconds? -> what equations should you use?
V = IR and I = Q/delta T -> Q = V * Delta T / R = (100 V)(10 s) / 2 ohms = 500 c; 500 C / 10^5 = 5 x 10^ -3
If the area of a capacitor’s plates is doubled whiel the distance between them is halved, how will the final capacitance compare to the original capacitance?
4x the original capacitance
The energy stores in a fully charged capacitor is given by U = 1/2 CV ^2. In a typical cardiac defibrillator, a capacitor charged to 7500 V has a stored energy of 400 J. Based on this information, what is the charge on the capacitor in the cardiac defibrillator?
U = 1/2 CV^2 = 1/2 (Q/V) V^2 = QV/2 ; Q = 2U/V = 2(400 J)/7500 V = 0.1 C
Which of the following will most likely increase the electric field between the plates of a parallel plate capacitor?
Adding an extra battery to the system
Which of the following best characterizes ideal voltmeters and ammeters?
Ideal voltmeters have infinite resistance, and ideal ammeters have no resistance
What is wave speed?
The rate at which a wave transmits the energy or matter it is carrying (product of frequency and wavelength)
What is frequency?
A measure of how often a waveform passes a given point in space (Hz)
What is angular frequency?
The same as frequency, but is measured in radians per second
What is period?
The time necessary to complete a wave cycle
What is equilibrium position?
The point with zero displacement in an oscillating system
What is amplitude?
The maximal displacement of a wave from the equilibrium position
What is a traveling wave?
Have nodes and antinodes that move with wave propagation
What is a standing wave?
Have defined nodes and antinodes that do not move with wave propagation
If two waves are out of phase at any interval besides 180 degrees, how does the amplitude of the resultant waves compare to the amplitudes of the two interfering waves?
Perfectly in phase = amplitude is equal to the sum of the amplitudes of the interfering waves ; perfectly out of phase = amplitude is equal to the difference of the amplitudes of the interfering waves
True or False: Sound waves are a prime example of transverse waves
FALSE, sound waves = longitudinal waves
How does applying a force at a natural frequency of a system change the system?
The object will resonate because the force frequency = the natural (resonant) frequency, amplitude of the oscillation will increase
How is sound produced and transmitted?
Mechanical vibrations (usually generated by solid objects like bells or vocal cords), but occasionally can be generated by fluids, propagated as longitudinal waves in matter
To which properties of a sound wave do amplitude and frequency correspond?
Amplitude is related to its sound level (volume), frequency is related to its pitch
If two objects are traveling toward each other/away from each other/one is following the other, how does the apparent frequency differ from the original frequency?
Traveling towards each other = apparent frequency > original frequency ; traveling away from each other = apparent frequency < original frequency ; one following the other = apparent frequency could be greater or less than original frequency
An opera singer has two precisely identical glasses. The singer produces as pure a tone as possible and shatters the first glass at a frequency of 808 Hz. She then sings a frequency of 838 Hz in the presence of the second glass. The second glass will likely:
Not shatter because the applied frequency is not equal to the natural frequency of the glass
What is a true statement about frequency, angular frequency, and period of a given wave?
The magnitude of the angular frequency is larger than the magnitude of the frequency
A student is measuring sound frequencies from the side of a road while walking east. For which of the following situations could the student determine that the difference between the perceived frequency and the actual emitted frequency is zero?
A dog barking in a car that moves east (would only be zero if moving in the same direction)
In which of the following media does sound travel the fastest?
Glass
Shock waves have the greatest impact when the source is traveling:
Exactly at the speed of sound
Ignoring attenuation, how does the intensity of a sound change as the distance from the source doubles?
It is one-quarter as intense
Order the types of electromagnetic radiation from lowest to highest energy/frequency.
Radio < Micro < Infrared < Visible < UV < X-rays < Gamma
True or False: Light waves are longitudinal because the direction of propagation is perpendicular to the direction of oscillation
FALSE! Light waves are transverse waves
What are the boundaries of the visible spectrum? How does the range of the visible spectrum compare to the range of the full electromagnetic spectrum?
ROYGBIV (700 -> 400 nm, increases in frequency)
What do the signs of variables mean for mirrors?
Positive o = in front of mirror, Negative o = behind mirror ; Positive i = in front of mirror (real) , Negative i = behind mirror (virtual) ; Positive r = concave (converging) , Negative r = convex mirror (diverging) ; Positive f = concave (converging) , Negative f = convex (diverging) ; Positive m = image is upright, Negative m = image is inverted
What do the signs of variables mean for lenses?
Positive o = on same side of lens, Negative o = on opposite side of lens ; Positive i = opposite side of lens (real) , Negative i = same side of lens (virtual) ; Positive r = convex (converging) , Negative r = concave mirror (diverging) ; Positive f = convex (converging) , Negative f = concave (diverging) ; Positive m = image is upright, Negative m = image is inverted
What is dispersion? What is aberration?
Dispersion = the tendency for different wavelengths of light to experience different degrees of refraction in a medium, leading to a separation of light into the visible spectrum (a rainbow) ; Aberration = the alteration or distortion of an image as a result of an imperfection in the optical system
How does the diffraction pattern for a single slit differ from a slit with a thin lens?
Diffraction through a single slit does not create characteristic fringes when projected on a screen, although the light does spread out. When a lens is introduced into the system, the additional refraction of light causes constructive and destructive interference, creating fringes.
What wave phenomenon do diffraction fringes result from?
Constructive and destructive interference between light rays
How does double-slit diffraction and interference differ from single-slit diffraction?
The image formed during double-slit diffraction contains fringes because light rays constructively and destructively interfere. A single slit forms an image of a wide band of light, spread out from its original beam
True or False: Maxima in diffraction patterns are always equidistant between two minima
True (maxima and minima alternate in a diffraction pattern)
Contrast plane-polarized and circularly polarized light.
Plane-polarized light contains light waves with parallel electric field vectors. Circularly polarized light selects for a given amplitude and has a continuously rotating electric field direction.
How does the application of a polarized filter impact the wavelength of light passing through the filter?
Plane polarization has no effect on the wavelength (or frequency or speed) of light. Polarization does affect the amount of light passing through a medium and light intensity.
If a light ray has a frequency of 5.0 x 10^14 Hz, in which region of the electromagnetic spectrum is it located?
c = f * lambda -> (3 x 10^8 m/s) / (5 x 10^14 Hz) = 6 x 10^-7 m = 600 nm = visible light
A child stands between two mirrors with his arms out, perpendicular to the mirrors. One plane mirror is 5 m away from his left hand and another plane mirror is 7 m away from his right hand. How far apart are the two images produced by the mirrors if the child has an arm span of 0.5 m?
Plane mirror is as far away from the image as the object is -> 7 + 7 + 5 + 5 + 0.5 = 24.5 m
An object is placed at the center of curvature of a concave mirror. Which of the following is true about the image?
1/f = 1/i + 1/o -> 1/f = 1/i + 1/2f -> 1/2f = 1/i -> i = 2f (Positive = real image, then has to be inverted)
A ray of light (f = 5 x 10^14 Hz) travels from air into crystal into chromium. If the indices of refraction of air, crystal, and chromium are 1, 2, and 3, respectively, and the incident angle is 30 degrees, then which of the following describes the frequency and the angle of refraction in the chromium?
5 x 10^14 Hz; 9.6 degrees (angle of refraction < incident angle)
A source of light (f = 6.0 x 10^14 Hz) passes through three plane polarizers. The first two polarizers are in the same direction, while the third is rotated 90 degrees with respect to the second polarizer. What is the frequency of the light that comes out of the third polarizer?
Light will not pass through the third polarizer
Which of the following describes the image formed by an object placed in front of a convex lens at a distance smaller than the focal length?
Virtual and upright (in front of focal point = has to be virtual)
A submarine is inspecting the surface of the water with a laser that points from the submarine to the surface of the water and through the air. At what angle will the laser not penetrate the surface of the water but rather reflect entirely back into the water?
sin (1/1.33) = 0.75 -> sin 45 = sqrt 2 / 2 = 0.707 = 48.59 degrees
A student is analyzing the behavior of a light ray that is passed through a small opening and a lens and allowed to project on a screen a distance away. What happens to the central maximum (the brightest spot on the screen) when the slit becomes narrower?
The central maximum becomes wider (equation: asintheta = nlambda -> a decreases, sin theta increases because nlambda is constant for a given slit)
Monochromatic red light is allowed to pass between two different media. If the incident angle in medium 1 is 30 degrees and the incident angle in medium 2 is 45 degrees, what is the relationship between the speed of the light in medium 2 compared to medium 1?
Using Snell’s law and n = cv, it becomes c1/v1 sin theta 1 = c2/v2 sin theta 2 -> sin 30/v1 = sin 45/v2 -> v2 = v1 sqrt (2)
A scientist looks through a microscope with two thin lenses with m1 = 10 and m2 = 40. What is the overall magnification of this microscope?
Magnification = 10 * 40 = 400
Imagine that a beam of monochromatic light originates in air and is allowed to shine upon the flat surfacce of a piece of glass at an angle of 60 degrees with the normal. The reflected and refracted beams are perpendicular to each other. What is the index of refraction of the glass?
Snell’s Law -> n1sintheta1 = n2sintheta 2 -> sin 60 = n2 sin 30 -> n2 = sqrt (3)
What is the approximate partial pressure of oxygen at 1500 m?
Dalton’s Law : 0.84 atm * 0.21 = 0.716 atm ~ 0.18 atm
A climber using bottled oxygen accidentally drops the oxygen bottle from an altitude of 4500 m. If the bottle fell straight down this entire distance, what is the velocity of the 3-kg bottle just prior to impact at sea level?
As an object falls, KE would end up equaling PE -> 1/2m(vfinal)^2 = mgh -> 1/2 (3)(vfinal)^2 = 3(10)(4500) -> vfinal = 300 m/s
Fluid pressure changes with depth are assumed to be linear. Which statement best explains why this does not hold true for atmospheric pressure changes?
The volume of a mass of air is not constant
Which of the following most closely approximates the pKa of phenolphthalein?
9.3 (cannot be under 7)
What is the letter for the amino acids asparagine and phenylalanine?
N and F
Which of the following phase changes are exothermic processes?
Liquid to solid, gas to solid (solids and liquids have less heat energy than gas)
When 2 moles of HF are added to 100 mL of water, the resulting solution has a pH equal to 4. What is the percent dissociation of HF?
Original [HF] = 2 mol/0.100 L = 20 M -> [H+]/[HF] = (10^-4 M)/(20 M) = 5 x 10^-6 -> % dissociation = 5 x 10^-6 x 100 = 5 x 10^-4 = 0.0005%
An object with a mass of 10 kg is rolled down a frictionless ramp from a height of 3 meters. If a factory worker at the bottom of the ramp slows the object until it comes to a stop, how much work must the factory worker have done? (Assume g = 10 m/s^2)
Gravitational potential energy = 10103 = 300 J -> work-energy theorem says that Wnet = change in KE -> delta KE = 300 J
What is the wavelength of the photons emitted by the 145Pm-m?
Lambda = hc/E -> (6.62 x 10^-34 J*s)(3 x 10^8 m/s) / (300 x 10^3 eV)(1.6 x 10^-19) = 4.1 x 10^-12 m
In order to find the concentration of metal ions needed to determine the distribution coefficient of copper (II), what calculation could the researchers have performed in addition to the procedure described in the passage?
Subtract the concentration of metal ions in the aqueous phase after extraction from the concentration before extraction
Following extraction into chloroform, the spectrophotometric absorbance at 820 nm of copper in aqueous solution will be greatest at which pH?
5.15 (the aqueous solution pH in which log D is smallest for the extraction of chloroform)
In the electron transport chain, which of the following is the component that is reduced but never oxidized?
Oxygen (is reduced to yield H2O, but is never shown to become oxidized)
What is a molecule with a carboxylic acid functional group that has a high Ka?
CH3CF2COOH (higher Ka = more acidic)
A 50-kg child is riding on a playground merry-go-round. If the radius of the circular path of the merry-go-round is 5.0 m and the frequency is 0.1 hertz, what is the force required to keep the child on the ride?
Centripetal force -> have to calculate speed first -> V = 2pi*r/T = 2(3.14)(5.0 m)/(10 s) = 3.14 m/s, then calculate centripetal force -> Fc = mv^2/r = (50 kg)(3.14 m/s)^2/(5.0 m) ~ 100 N
Cefimixe displays what inhibitive behavior on PBP?
Only irreversible enzyme inhibitor = suicide inhibitor
If a strong base solution used in the titration curve shown was 0.10 M sodium hydroxide and the volume of the glycine solution titrated was 20.0 mL, what was the molarity of the glycine solution?
15 mL NaOH * (0.10 mole/L) * (1 glycine/1 NaOH) * (1/20 mL) = 0.075 moles/L
Which of the following represents the pH of the isoelectric point for glycine?
On a titration curve, this can be approximated by averaging the midpoints of the two plateau regions
What is the mechanical advantage of using the ramp, as opposed to lifting the gurney straight up? (Ignore any effects of friction)
MA = hypotenuse / height = 2x / x = 2
Two identical gurneys are placed side-by-side on a ramp with their wheels locked to eliminate spinning. Gurney 1 has a dummy placed on it to give it a total mass of 200 kg, while Gurney 2 is loaded with a dummy that makes it only 50 kg overall. If the ramp has a coefficient of friction of ustatic, which gurney is more likely to slide down the ramp?
They are equally likely to slide down the ramp (gurney with a larger mass also has a larger static frictional force)
A circuit is comprised of a 12-volt battery with three light bulbs with the same resistance. If two of the light bulbs are wired in parallel and are in series with the three light bulb, what happens when one of the parallel light bulbs is unscrewed?
Two of the light bulbs remain lit
Air is bubbled through distilled water. The solution will have a pH:
Less than 7, because carbon dioxide undergoes hydrolysis (carbon dioxide -> carbonic acid, pH < 7)
What is the approximate pH of a saturated aqueous solution of hydrochloric acid whose molarity is 10.6 M?
Saturated HCl would completely dissociates in aqueous solution, pH = -log [OH] = -log [10] = -log [10^1] = -1
Which molecule will have the highest Rf value studied with thin-layer chromatography using a silica plate?
CH3CH2CH2CH2CH3 (the most nonpolar compound)
Atherosclerosis, a particular type of arteriosclerosis, usually involves either complete blockage or severe restriction of blood flow due to high cholesterol and buildup of plaque in the arteries. In extreme cases, constricted arteries may collapse under pressure from outside the arteries. This can best be explained by:
The necessary increase in fluid velocity through the constricted arterial sections causing a corresponding drop in fluid pressure
An artificial heart valve was tested for its ability to function under extreme conditions, to a maximum flow rate of 4.00 x 10^-4 m^3/s. What speed would this correspond to for an average red blood cell within a blood vessel of cross-sectional 5.00 x 10^-6 m^2?
Speed = (4 x 10^-4 m^3/s) / (5 x 10^-6 m^2) = 8 x 10^ 1 m/s
Underproduction of pulmonary surfactant in IRDS leads to decreased compliance of alveolar tissue. Based upon this information, which of the following must be true regarding pulmonary surfactant?
Its adsorption to the water-alveolar interface decreases surface tension, decreasing the pressure difference required to inflate the airway
What occurs doing inspiration?
Contraction of the diaphragm and external intercostal muscles -> expansion of the thoracic cavity, decrease in intrapleural pressure (negative pressure relative to atmosphere causes airflow through the respiratory tree)
For an interaction to be spontaneous…
The free energy change of the reaction must be negative
Which of the following electronic transitions for a hydrogen atom would result in the emission of a photon that would be visible to the human eye?
n = 4 to n = 2 ( E = Rydberg constant (1 x 10^7 m^-1) / n^2)
The transition from N to O offers an exception to the trend for first ionization energy due to Hund’s rules of spin pairing. If this spin pairing was not present, what would be the expected first ionization energy for the p-orbital on an oxygen atom?
There is a trend exception from group 5 to group 6 (ionization energy would be higher if there was no drop in IE)
Which of the following explains the observations made by Rutherford?
Most of the volume of the gold atom is empty space, the alpha particles and the gold nuclei are both positively charged
Which of the following types of electromagnetic radiation would have the shortest wavelength?
Radiation that ejects an electron from an sp orbital (shorter wavelength = higher energy; sp = triple bond)
A person pushes horizontally on a 50-kg crate, causing it to accelerate from rest and slide across the surface. If the push causes the crate to accelerate at 2.0 m/s^2, what is the velocity of the crate after the person has pushed the crate a distance of 6 meters?
Vf^2 = Vi^2 + 2ad = 0^2 + 2(2)(6) = 5 m/s
Does lithium have the second largest atomic radius in period 2?
No
How much heat is produced from the complete combustion of 30 g of methane, if the enthalpy of reaction is -890 kJ/mol?
30 g CH4 x (1 mol/16 g) x (890 kJ/mol) = 1.8 x 10^3 kJ
What is the exclusion limit of the SEC column used to create the calibration curve shown in Figure 2?
If log (MW) = 6, MW = 10^6 Da = 10^3 kDa = 1000 kDa
What is affinity chromatography?
Used to separate molecules, including proteins, based upon their specific interaction with the stationary phase
What is ion-exchange chromatography?
The ion listed is the one that takes longer to elute (ex. cation exchange chromatography = negatively charged resin, cation bind and take longer to elute)
What is SDS-PAGE?
An electrophoretic technique which involves the binding of the anionic detergent SDS to a polypeptide chain (fractionation by approximate size alone during electrophoresis)
What is NMR spectroscopy?
Not a separatory technique (can fraction a protein sample based on only molecular weight)
More complete fractionation of proteins using an SEC column could be achieved by using a:
Longer column
Selenocysteine is a non-standard amino acid that is present in all domains of life. It has the structure of cysteine, but the sulfur atom is replaced with selenium. What is the absolute configuration of the alpha carbon in selenocysteine?
R (R, S = absolute configuration; D, L = relative configuration)
Which acids (HF, HCl, HBr, and HI) is a weak acid in aqueous solution?
HF
What is the pH of a 0.10 M aqueous solution of acetylsalicylic acid?
Ka = [H+][A-]/[HA] -> 10^-35 = x^2/0.1 -> pH = 2.25
A student determined that her yield of aspirin was 3.9 g. What was her percent yield?
3.5 x 10^-2 mol * 180 g/mol ~ 7g -> 4/7 = 60%
Salicylic acid is a benzoic acid derivative which can most directly be obtained through the Kolbe-Schmitt carboxylation of:
A phenol
Which pair of enzymes, if used simultaneously, will produce the greatest amount of glucose if the experiment is repeated?
The pair of enzymes that have the maximum current/absorbance
How would the absorbance at 570 nm change over time for enzyme A if a linear starch was used?
Enzyme A would break down linkages, forming more linear polysaccharides, but if the initial starch is entirely linear, than a debranching enzyme would have no effect on absorbance
Phosphorous acid, a common ingredient used for portable water treatment, has a molecular formula of:
H3PO3
During strenuous exercise, lactic acid buildup in cells causes the creation of a hydronium complex known as the Eigen cation (H9O4+). If water molecules then experience hydrogen bond attractions to the Eigen cation, this attractive force:
Results in a semi-stable shell of water molecules around the hydronium
If a 3-kg rabbit’s leg muscles act as imperfectly elastic springs, how much energy will they hold if the rabbit lands from a height of 0.5 m and its legs are compressed by 0.2 m?
PE = (3)(10)(0.5) = 15 J, which is a bit of an overestimate, closest to 10 J
When does a runner output the most additional energy to keep the ground reaction forces most nearly vertical and through her body’s center of mass?
When she takes high, bouncing strides and leans her upper half into her run
A 60-kg runner raises his center of mass approximately 0.5 m with each step. Although his leg muscles act as a spring, recapturing the energy each time his feet touch down, there’s an average 10% loss with each compression. What must the runner’s additional power output be to account for just this loss, if he averages 0.8 s per stride?
PE = (60 kg)(10 m/s^2)(0.5 m) = 300 J -> 10% of 300 J = 30 J -> Power = (30 J)/(0.8 s) = 40 W
Which of the following best explains why arginine is more basic than lysine?
The electron-donating groups around the basic nitrogen on arginine make its conjugate acid more stable
In a flat Petri dish contaning a single layer of cells suspended in viscous culture medium is tapped, some cells will collide into each other. If cell 1 collides into cell 2 on such a plate, which of the following describes what happens to cell 2 after the collision, assuming that it undergoes an elastic collision and experiences drag from the medium?
Cell 2 moves with decreasing speed, Cell 2 decelerates until it reaches a velocity of 0 m/s
Balance the following redox reaction using the half-reaction method: Mg (s) + HNO3 (aq) -> Mg2+ (aq) + NO (g)
2 HNO3 + 3 Mg + 6 H+ -> 2 NO + 3 Mg2+ + 4H2O
A sample is assayed for lead by a redox titration with I3- (aq). A 10.00 g sample is crushed, dissolved in sulfuric acid, and passed over a reducing agent so that all the lead is in the form Pb2+. The Pb2+ (aq) is completely oxidized to Pb4+ by 32.60 mL of a 0.7 M solution of NaI3. The balanced equation for the reaction is: I3- + (aq) + Pb2+ (aq) -> Pb4+ (aq) + 3I- (aq). Calculate the mass of lead in the sample.
0.7 M I3- (32.60 x 10^-3 L) (1 mol Pb2+/1 mol I3-) (207.2 g Pb2+/1 mol Pb2+) ~ 4.2 g
Consider the following equation: 6 Na (s) + 2 NH3 (aq) -> 2Na3N (s) + 3 H2 (g). Which species acts as an oxidizing agent?
H in NH3
As methanol is converted to methanal, and then methanoic acid, the oxidation number of the carbon:
Increases
If a certain metal has multiple oxidation states, its acidity as an oxide generally increases as the oxidation state increases. Therefore, which of the following tungsten compounds is likely to be the strongest acid?
WO3
What is a disproportionation reaction?
When a reactant results in two different oxidation states in two different products
The equation is Au + NaCN + O2 + H2O -> Na [Au(CN)2] + NaOH. An indicator is used during this reaction, and approximately 100 mL of a 2M NaCN solution is used to reach the endpoint. How many moles of Au are present in the crushed ore?
Balanced equation: 4Au + 8NaCN + O2 + 2H2O -> 4Na [Au(CN)2] + 4NaOH -> 0.1 L * 2 mol/L = 0.2 mol NaCN -> 0.2 mol * 4 mol Au/8 mol NaCN = 0.1 mol Au
What statements describe a galvanic (voltaic) cell?
Anode = site of oxidation, current flows cathode -> anode, anode has a negative designation, electrons flow anode -> cathode
What statements describe an electrolytic cell?
Anode = site of oxidation, current flows cathode -> anode, cathode has a negative designation, electrons flow anode -> cathode
Write the cell diagram for the discharging state of a lead-acid battery.
Pb (s) I H2SO4 (4 M) II H2SO4 (4 M) I PbO2 (s)
How much current is required to produce 0.23 kg Na from a molten NaCl electrolytic cell that runs for 30 hours? Assume the cell is 100% efficient.
mol M = It/nF -> I = (mol M)nF / t = (230 g/23 g/mol) (1 mol e-)(96,485 C/mol e-) / 30 hr (3600 s / 1 hr) = 10 A
How are standard reduction potentials measured?
Setting up a cell relative to a standard hydrogen electrode, which is given a reduction potential of 0 V by convention
What does it mean if the emf is positive/negative?
Positive emf = spontaneous (galvanic); negative emf = nonspontaneous (electrolytic)
If Keq is very large, the reaction is ___. If Keq is very small, the reaction is ____.
Spontaneous/nonspontaneous
An electrolytic cell is filled with water. Which of the following will move toward the cathode of such a cell?
H+ ions and electrons
