Physics 1
what is the work done when velocity is constant?
0 since w=CHANGE in KE, no velocity change means no KE change
What is the equation for force of static friction in terms of normal force?
0 ≤ static friction ≤ (coefficient of static friction)·(normal force) Static friction is equal and opposite to the direction of the force along a surface up to the point where it equals the product of the normal force and the coefficient of static friction (μs).
What is the Sin of 0, 30, 60, 90? Cos?
0, .5, .7, .9 sin 1, .9, .7, .5, 0 cos
What equation is used to relate the Resistance (R1, R2, etc) across all of the resistors to the total Resistance (Rt) of a circuit when resistors are in parallel?
1 / Rt = (1/R1) + (1/R2)... (1/Rn)
What is the equation for pressure of a fluid at a given depth in terms of density (with no atmosphere)?
Pressure = ρhg ρ = density h = depth from top of fluid g = acceleration due to gravity (9.8 m/s^2)
What does vector b̂ = 4î + 3ĵ mean?
Vector b can be broken down into a horizontal vector of length 4 and a vertical vector of length 3.
What is the work equation when the force is applied at an angle? What does wok equal if the force is perpendicular to the motion?
W=Fdcostheta w=0 (like pushing down on a ball, no movement
Give the work equation in terms of Mass.
W=m*a*d since F=ma
What is the pressure of water in a vacuum at a depth of 4.78 m? (A) 46,844 (B) 57,391 (C) 89,648 (D) 104,589
(A) 46,844 ρH2O = 1000 kg/m^3 <- You should have this memorized! Pressure = ρhg Pressure = (1000)(4.78)(9.8) Pressure = 49,000 pascals (actual: 46,844)
The total Voltage for a circuit with resistors in series is equal to 4.7 V. If R1 = 2.3 Ω, R2 = 6.5 Ω, and R3 = 9.7 Ω, what is the current? (A) .254 (B) .463 (C) 1.12 (D) 3.87
(A) .254 Rt = R1 + R2 + R3 Rt = 2.3 + 6.5 + 9.7 Rt = 18.5 Ω V = IR 4.7 = I (18.5) I = 4.7 / 18.5 I = approx. .25 (actual: .254)
A liquid is flowing through a pipe of length 4 m, with a velocity of 10 m^3/s. The radius of the tube is 2 m, and there is a pressure difference of 1,000 Pa from one end of the pipe to the other. What is the coefficient of Viscosity for this fluid (in Pa*s)? (A) 0.125 (B) 1.47 (C) 18.9 (D) 0.00232
(A) 0.125 V/t = velocity x Area V/t = 1000(π(2)^2) = 4000π m^3/s V/t = (∆Pπr^4)/(8ηL) (4000π) = (1,000)(π)(2^4)/((8)(η)(4)) η = 16,000π/(128,000π) = 0.125 Pa·s
A proton (q = 1.602⋅10^-19 C) is travelling through a magnetic field (B = .27 T) at an angle of 47° with a velocity of 4.5⋅10^7 m/s. What is the Magnetic Force acting on this proton? (A) 1.42⋅10^-12 (B) 6.78⋅10^-13 (C) 9.22⋅10^-14 (D) 3.09⋅10^-15
(A) 1.42⋅10^-12 F = qvBsinθ F = (1.602⋅10^-19) (4.5⋅10^7)(.27)sin47° F = (1.602⋅10^-19) (4.5⋅10^7)(.27)(approx. √2/2 or .7 (actual: .731)) F = approx. 1.5⋅10^-12 (actual: 1.423⋅10^-12)
10L of a gas with an internal energy of 3.8J is compressed by a force of 131J at a constant temperature. What is the new internal energy of the gas? (A) 134.8 J (B) 144.8 J (C) 124.8 J (D) 169 J
(A) 134.8 J ΔU = Q + W Q did not change W= 131J ΔU = 131 Utotal= 3.8+131=134.8J
Water is flowing through a level pipe. One end of the pipe has an area of 4 m^2, while the other end has an area of 1/4 m^2. The pressure at the entrance is 200,000 Pa, while the pressure at the exit is 100,000 Pa. What is the Flow Rate in the pipe (m^3/s)? (A) 3.54 (B) 53.33 (C) 0.8769 (D) 112.47
(A) 3.54 v1A1 = v2A2 = Flow Rate = R v1 = R/4 v2 = R/(.25) = 4R P1 + 1/2ρv1^2 + ρgh1 = P2 + 1/2ρv2^2 + ρgh2 (200,000) + (.5)(1000)(R/4)^2 + (1000)(9.8)(h) = (100,000) + (.5)(1000)(4R)^2 +(1000)(9.8)(h) Subtract (1000)(9.8)(h) from each side (200,000) + (.5)(1000)(R/4)^2 = (100,000) + (.5)(1000)(4R)^2 100,000 + ( 500)(R/4)^2 = 500 (4R)^2 100,000 = 500 ((4R)^2-(R/4)^2) 200=16R^2 - R^2/16 200=(255/16)R^2 12.54=R^2 (Approximately 10) 3.54=R (Approximately 3) R = approx. 3 m^3/s (3.54 m^3/s)
q1 (3.4⋅10^-14 C) and q2 (2.1⋅10^-9 C) are exactly 3.2⋅10^-3 m apart. What is the value of the Electrostatic Force (in N) between these two charges (k = 9⋅10^9)? (A) 6.27⋅10^-8 (B) 3.24⋅10^-9 (C) 9.66⋅10^-20 (D) 7.32⋅10^-21
(A) 6.27⋅10^-8 Fe = k ((q1q2) / r^2) Fe = (9⋅10^9) (((3.4⋅10^-14)(2.1⋅10^-9)) / (3.2⋅10^-3)^2) Fe = (9⋅10^9) (((approx. 7⋅10^-23 (actual: 7.14⋅10^-23))) / (3.2⋅10^-3)^2) Fe = (9⋅10^9)⋅(approx. 7⋅10^-18 (actual: 6.97⋅10^-18)) Fe = approx. 6⋅10^-8 N (actual: 6.27⋅10^-8)
You are reducing copper, and decide to double the number of moles of copper that you are reducing. If you do so, the: I. ∆G° will double II. E°red for copper will double III. K will double (A) I Only (B) II Only (C) I and II Only (D) I and III Only
(A) I Only You are reducing copper, and decide to double the number of moles of copper that you are reducing. If you do so, the ∆G° will double and n will double, leaving the E°red as the same value according to the relationship ∆G° = -nFE°cell. K will not change according to the relationship -nFE°cell = -RTlnK.
Find the volume of 1.9*10^24 molecules of He gas under STP conditions. (A) 71 L (B) 0.159 L (C) 16 L (D) 0.071 L
(A)71 L PV=NkBT P= 101,325 Pa N= 1.9*10^24 molecules T= 273 K kB= 1.38 x 10^-23 J/K (101325)V=(1.9*10^24)(1.38 x 10^-23)(273) V= About 10000/101325 V= about 0.1 m^3 (Exactly .071 m^3) (0.1m^3)(1000L/m^3)= 100L (Exactly 71 L)
f a box (9.88 kg) is moving at 11.32 m/s and is slowed by friction until the velocity is 4.89 m/s, what is the work done by friction (in J)? (A) -751 (B) -515 (C) 515 (D) 751
(B) -515 Work = change in kinetic energy KE = 1/2 mv^2 ΔKE = 1/2 (9.88)(4.89)^2 - 1/2 (9.88)(11.32)^2 ΔKE = (approx. 125 (actual: 118)) - (approx. 600 (actual: 633)) Work done = approx. -475 (actual: -515)
If a spring is exerting a force of 7.23 N at a displacement of -9.65 m, what is the spring constant for that spring? (A) .642 (B) .749 (C) .813 (D) .893
(B) .749 Force = 7 N Displacement = approx. -10 m (actual -9.65 m) F = -kx 7.23 = -k (-9.65) k = 7.23/ 9.65 k = approx. .75 (actual: .749)
A Test Charge (2.5⋅10^-16 C) is nearby a Source Charge (7.8⋅10^-13 C). If the Fe is equal to 45.7 N, what is the strength of the Electric Field? (A) 7.65⋅10^-15 N/C (B) 1.83⋅10^17 N/C (C) 4.43⋅10^-17 N/C (D) 9.32⋅10^18 N/C
(B) 1.87⋅10^17 C/m Fe / q = E E = 45.7 / 2.5⋅10^-16 E = approx. 2⋅10^17 N/C (actual: 1.83⋅10^17)
Johnny does 209.87 J of work to a box of mass 4.04 kg that was sitting still on frictionless ice. What is the velocity of the box (in J)? (A) 5.67 (B) 10.19 (C) 16.78 (D) 24.67
(B) 10.19 Work = approx. 210 J In this example, all of that work is converted to kinetic energy, so KE = approx 210 J KE = 1/2 mv^2 209.87 = 4.04/2 V^2 approx. 100 (actual: 103.9) = v^2 v = approx. 10 m/s (actual: 10.19)
How much power does it take to lift a 96.57 kg weight 1.34 m into the air in 7.25 seconds? (A) 97.65 (B) 174.92 (C) 302.65 (D) 425.43
(B) 174.92 Work Done = PE = mgh PE = (96.57)(9.8)(1.34) = approx. 1000 J (actual: 1268.16) Power = work/time Power = 1268.16 J / 7.25 s Power = approx. 200 J/s (actual: 174.92)
If a gas has a pressure of 10,000 Pa, a volume of 3 m^3, and there are 2 moles of gas, what is the temperature of the gas? (A) 1308 (B) 1804 (C) 2398 (D) 3254
(B) 1804 PV = nRT (10,000)(3) = (2)(8.314)T T = 1804 K
Joshua drove 17.45 miles in 23.4 minutes. His total displacement, however, was only 9.44 miles in the north direction. What was his average velocity (in mph)? (A) 13.5 (B) 24.2 (C) 43.6 (D) 67.2
(B) 24.2 Average velocity = displacement/change in time Average Velocity = (9.44 miles) / (23.4/60 hour) Average Velocity = (9.44 miles) / (approx. 1/3 hour) Average Velocity = approx. 30 mph (actual: 24.2)
If the pressure of a gas is 987,000 Pa, and the mol fraction of O2 in that gas is .32, what is the partial pressure of O2? (A) 224,650 (B) 315,840 (C) 436,780 (D) 658,930
(B) 315,840 Pa = Xa x Pt Partial pressure = mole fraction times total pressure Partial Pressure of O2 = 987,000 (.32) Partial Pressure of O2 = approx. 320,000 Pa (actual: 315,840)
Assuming no friction, what would be the net force acting on a box on an incline angled at 30 degrees, with a weight of 10N? (A) 3 (B) 5 (C) 8 (D) 15
(B) 5 Angle = 30 degrees *No friction. *Normal force cancels out the perpendicular force of gravity. Net force = Parallel force of gravity = 10N x sin30 = 5N
If a fluid is flowing at 2.09 m/s through an area of 8.79 m^2, what is the velocity of the water when the pipe sqeezes down to an area of 3.42 m^2? (A) 3.64 (B) 5.37 (C) 8.33 (D) 14.60
(B) 5.37 v1A1 = v2A2 (2.09)(8.79) = (3.42)(v2) v2 = 5 m/s (actual: 5.37)
You have three capacitors in series (C1 = 2.6 F, C2 = 7.4 F, C3 = 2.2 F) and connected to a battery (V = 13.3 V). What is the voltage across C3? (A) 3.12 (B) 6.05 (C) 13.24 (D) 19.44
(B) 6.05 1/Ceq = 1/C1 + 1/C2 + 1/C3 1/Ceq = 1/2.6 + 1/7.4 + 1/2.2 1/Ceq = approx. 1 (actual: .974) Ceq = approx. 1 (actual: 1.03) Ceq = Q / V 1.03 = Q / 13.3 Q = approx. 13.3 (actual: 13.7) C3 = Q / V3 2.2 = 13.3 / V3 V3 = approx. 6 (actual: 6.05)
A liquid is in a horseshoe shaped test tube with one side large than the other. If a force of 9.67 N is spread across the liquid with an area of 1.89 m^2, what would the force of the liquid be on the other side of the test tube, which has an area of 13.24 m^2? (A) 45.63 (B) 67.74 (C) 89.40 (D) 112.89
(B) 67.74 F1/A1 = F2/A2 (9.67)/(1.89) = F2/(13.24) F2 = approx. 70 N (actual: 67.74)
Water is flowing through a pipe of varying cross sectional area down a hill with a velocity of 10 m/s at the top and 20 m/s at the bottom. Over this distance, the pipe goes from a height of 10 m to a height of 0 m. The water is at a pressure of 1,000,000 Pascals at the top. What is the pressure at the bottom (use 10 m/s^2 for g for simplicity)? What would you do if one of the Velocities was not given to you but only area of the openings? (A) 820,000 (B) 950,000 (C) 1,240,000 (D) 1,560,000
(B) 950,000 P1 + 1/2ρv1^2 + ρgh1 = P2 + 1/2ρv2^2 + ρgh2 (1000000) + (.5)(1000)(10^2) + (1000)(10)(10) = P2 + (.5)(1000)(20^2) + (1000)(10)(0) 1150000= P2 + 200000 P2 = 950,000 Pa If one Velocity was not given we could use the area to solve for velocity using the continuity equation. Then you would plug into bernoulli's. Even without either you could save for a common variable R (flow rate) given the areas.
You have a simple circuit that contains a single resistor. If you increase the voltage, which of the following is true? I. Resistance increases. II. Current increases. III. Capacitance increases. (A) I Only (B) II Only (C) I and II Only (D) II and III Only
(B) II Only If you increase the voltage, the current will increase. Resistance (if it is an Ohmic material) will remain the same as it is a property that is dependent solely on the resistor and not on the batter or wire of the circuit.
You increase the charge on a Capacitor; therefore, the: I. Capacitance increases II. Voltage increases III. Resistance increases (A) I Only (B) II Only (C) I and II Only (D) II and III Only
(B) II Only You increase the charge on a Capacitor; therefore, the Voltage increases. The capacitance (just like resistance) will only change if you change its intrinsic characteristics.
When a capacitor is charged up and then disconnected from a battery, adding a dielectric will: I. Increase the voltage II. Increase the charge III. Increase the capacitance (A) I Only (B) III Only (C) I and III Only (D) II and III Only
(B) III Only A dielectric will increase the capacitance of a capacitor, which will allow more charge to build up on the capacitor. It will not affect the charge, but will actually decrease the voltage. This is because the induced polarization within the dielectric will effectively cancel out the charges on the plates, making the voltage difference between the two plates smaller.
Oxidation occurs at the _________. Reduction occurs at the ___________. (A) anode, anode (B) anode, cathode (C) cathode, cathode (D) cathode, anode
(B) anode, cathode Oxidation occurs at the anode. Reduction occurs at the cathode.
Voltage is _______ in positively-charged regions and _________ in negatively-charged regions. (A) high, high (B) high, low (C) low, low (D) low, high
(B) high, low Voltage is high in positively-charged regions and low in negatively-charged regions.
Voltmeters are hooked up in __________. Ammeters are hooked up in ___________. (A) parallel, parallel (B) parallel, series (C) series, series (D) series, parallel
(B) parallel, series Voltmeters are hooked up in parallel. This is because you want to measure the voltage different between two points without interfering with the circuit. Ammeters are hooked up in series. This is because you want to measure the current flowing through the circuit.
Electric Field Lines are drawn in the direction that a _________ Test Charge would move. (A) neutral (B) positive (C) negative (D) energized
(B) positive Electric Field Lines are drawn in the direction that a positive Test Charge would move.
Capacitor plates are hooked up to opposite ends of a battery. The plate connected to the positive terminal of the battery will end up ___________ charged. The plate connected to the negative terminal of the battery will end up ___________ charged. (A) positively, positively (B) positively, negatively (C) negatively, negatively (D) negatively, positively
(B) positively, negatively Capacitor plates are hooked up to opposite ends of a battery. The plate connected to the positive terminal of the battery will end up positively charged. The plate connected to the negative terminal of the battery will end up negatively charged.
Blood has a Coefficient of viscosity of .004 Pa·s, and a Reynolds number of 2000. If the density of blood is 1060 kg/m^3, and the radius of the aorta is .01 m, what is the critical speed for blood in the aorta? (A) .08 (B) .22 (C) .38 (D) .59
(C) .38 Critical speed = (Rη)/(2ρr) Critical Speed = (2000)(.004)/((2)(1060)(.01)) Critical speed = .approx. .4 (actual: .38 m/s)
A block is sitting on a flat surface, with a weight of 100 N. If it takes a force of 73 N to just barely start moving the block, what is the coefficient of static friction (μs)? (A) .54 (B) .62 (C) .73 (D) .81
(C) .73 Fs ≤ μs·Fn 73 = μs x 100 μs = 73 N/100 N μs = 0.73
One unit used for viscosity is a Poise. Which of the following is 1P equal to? (A) 1 Pa*s (B) 10 Pa*s (C) 0.1 Pa*s (D) 0.001 Pa*s
(C) 0.1 Pa*s One Poise is equal to 1/10 of a Pa*s so 10P=1Pa*s
Cu2+ (E°red = .34) with a concentration of 3.2⋅10^-3 M and Zn2+ (E°red = -.76) with a concentration of 4⋅10^-5 M are both part of a Galvanic Cell. What is Ecell for this cell under these conditions? (A) .54 (B) .95 (C) 1.06 (D) 1.34
(C) 1.06 E°cell = E°red (cathode) - E°red (anode) E°cell = .34 - -.76 E°cell = 1.00 Ecell = E°cell - (.0592 / n)logQ Ecell = 1 - (.0592 / 2)log(4⋅10^-5 / 3.2⋅10^-3) Ecell = 1 - (.0296)log(approx. .01 (actual: .0125) Ecell = 1 - (.0296)(approx. -2 (actual: -1.903)) Ecell = 1 - (.approx. -.05 (actual: -.056)) Ecell = approx. 1.05 (actual: 1.056)
Johnny gets on the elevator. He has a mass of 103.54 kg (too many sweets, Johnny). The elevator starts accelerating upwards at 2.13 m/s^2. What is the Normal force acting on Johnny (in N)? (A) 786.34 (B) 942.01 (C) 1235.23 (D) 1654.90
(C) 1235.23 Force of Gravity = 103.54 x -9.8 = -980 N (-1014.69) Net Force = 103.54 kg x 2.13 m/s^2 = 200 N (actual: 220.54) Force of Gravity + Normal force = Net Force -1014.69 N + Normal Force = 220.54 N Normal Force = 1180 N (actual: 1235.23)
Knowing that the specific heat of liquid water is 4.18J/g*C, how much energy must be added for 1g of water to increase its temperature from 5°C to 35°C (in J)? (A) 15 (B) 30 (C) 125 (D) 0.30
(C) 125 C = Q/ΔT so Q=C* ΔT ΔT= 35-5=30 C= 4.18 Q= 30*4.18 = about 120J (really 125)
You have three capacitors in parallel (C1 = 2.6 F, C2 = 7.4 F, C3 = 2.2 F) and connected to a battery (V = 13.3 V). What is the voltage across C3? (A) 2.56 (B) 7.09 (C) 13.30 (D) 21.34
(C) 13.30 The voltage across each capacitor is exactly the same in a parallel configuration
A box with a mass of 1 kg is pushed by a force of 20N. The coefficients of static and kinetic friction are .5 and .4, respectively. What is the net force on the box the moment it starts moving (in N)? While its moving? (A) 16.1 (B) 23.3 (C) 15.1 (D) 34.2
(C) 15.1 Mass = 1 kg Coefficient of static friction = .5 Normal force = (perpendicular force) Normal force = gravity = 1 kg x 9.8m/s^2 = 9.8 N Friction = normal force x coefficient of friction Static friction = 9.8 N x .5 = 4.9 N Net force = Sum of all forces Gravity and Normal force cancel out, force - friction Net force at beginning of movement = 20 N - 4.9 N = 15.1 N
The proton (1.67⋅10^-27 kg) in the most recent practice problem was acted on by a force of 1.42⋅10^-12 N and had a velocity of 4.5⋅10^7 m/s. What is the radius of the circle that this proton is moving in? (A) 4.56⋅10^-2 (B) 2.41⋅10^-1 (C) 2.38⋅10^0 (D) 8.76⋅10^1
(C) 2.38⋅10^0 Fm = Fc = m (v^2 / r) 1.42⋅10^-12 = 1.67⋅10^-27 ((4.5⋅10^7)^2 / r) 1.42⋅10^-12 = 1.67⋅10^-27 (approx. 2⋅10^15 (actual: 2.025⋅10^15) / r) 1.42⋅10^-12 = (approx. 3⋅10^-12 (actual: 3.38⋅10^-12)) (r) r = approx. 2 (actual: 2.38)
If a box has a mass of 5.34 kg, and is pushed by a spring for 4.89 m, giving it a velocity of 11.29 m/s, what is the spring constant for that spring (in N/m)? (A) 14.5 (B) 21.5 (C) 28.5 (D) 43.5
(C) 28.47 KE = 1/2 mv^2 KE = (.5)(5.34)(11.29)^2 KE = approx. 350 J (actual: 340) KE = PE = 1/2 kx^2 340 J = k(.5)(4.89)^2 k = approx. 30 kg/s^2 (actual: 28.5) Note: kg/s^2 is equivalent to N/m
You have three capacitors in parallel (C1 = 2.6 F, C2 = 7.4 F, C3 = 2.2 F) and connected to a battery (V = 13.3 V). What is the charge on a plate of C3? (A) 12.27 (B) 18.79 (C) 29.26 (D) 48.30
(C) 29.26 C3 = Q3 / V 2.2 = Q3 / 13.3 Q3 = approx. 30 (actual: 29.26)
If a 18.77 N box is sitting on one end of a lever at a distance of 1.32 m from the fulcrum, how much force must be applied to at a distance of 4.35 m from the fulcrum to raise the box? (A) 3.43 (B) 4.89 (C) 5.70 (D) 7.42
(C) 5.70 f1 x d1 = f2 x d2 18.77 x 1.32 = 4.35 x f2 f2 = approx. 6 N (actual: 5.70)
Cu2+ (E°red = .34) and Zn2+ (E°red = -.76) are both part of a Galvanic Cell. What is the equilibrium constant K for this cell? (A) 3.05⋅10^6 (B) 8.90⋅10^14 (C) 6.03⋅10^33 (D) 3.44⋅10^45
(C) 6.03⋅10^33 E°cell = E°red (cathode) - E°red (anode) E°cell = .34 - -.76 E°cell = 1.00 E°cell = (.0592 / n)logK 1.00 = (.0592 / 2)logK logK = approx. 30 (actual: 33.78) K = approx. 1⋅10^30 (actual: 6.03⋅10^33)
If the coefficient of viscosity if 4.34 Pa·s, the velocity of a boat along the surface of the liquid is 48.79 m/s, the area of the boat in contact with the fluid is 2.23 m^2, and the depth of the fluid is 5.54 m, what is the Force of viscosity on that object? (A) 45.63 (B) 63.42 (C) 85.23 (D) 98.46
(C) 85.23 F = η A v/d F = ((4.34)(2.23)(48.79))/(5.54) F = approx. 80 N (actual: 85.23)
Sally is pushing a box along the floor to the right with a constant velocity of 4.23 m/s. Which of the following is true? I. Sally is exerting a force on the box. II. The box is experiencing a net force of zero. III. The box is falling with a constant acceleration. (A) I Only (B) II Only (C) I and II Only (D) I, II, and III
(C) I and II Only I. Sally is exerting a force on the box. This is true! II. The box is experiencing a net force of zero. This is also true because the frictional force is equal to the force exerting by Sally; thus, the box is moving at a CONSTANT velocity and is not accelerating. III. The box is falling with a constant acceleration. This is false because gravity is opposed by the equal and opposite normal force.
Which of the following is equal to 1 Pascal (1Pa)? (A) m*s/N (B) N/ (m*s) (C) N/ m^2 (D) N/(m^2*s)
(C) N/ m^2 One Pascal is equal to one Newton per square meter. Remember, pressure is a force over an area!
In which direction does normal force push an object? (A) Straight up into the air. (B) At a 90 degree angle to the earth. (C) Perpendicular to the surface that the object is pushing against. (D) Perpendicular to the center of mass that the object is pushing against.
(C) Perpendicular to the surface that the object is pushing against.
Which of the following correctly describes why an airplane is lifted off of the ground using the Venturi Effect? (A) The velocity of the air under the wings is greater than the velocity of air above the wings, creating a higher pressure under the wings, giving the airplane lift. (B) The velocity of the air under the wings is greater than the velocity of air above the wings, creating a lower pressure under the wings, giving the airplane lift. (C) The velocity of the air under the wings is less than the velocity of air above the wings, creating a higher pressure under the wings, giving the airplane lift. (D) The velocity of the air under the wings is less than the velocity of air above the wings, creating a lower pressure under the wings, giving the airplane lift.
(C) The velocity of the air under the wings is less than the velocity of air above the wings, creating a higher pressure under the wings, giving the airplane lift.
Li- (E°red = -3.05) and Zn2+ (E°red = -.76) are both part of a Galvanic Cell. What is the Standard Gibb's Free Energy (in J) for this cell? (A) -54,978 (B) -110,574 (C) -221,453 (D) -441,970
(D) -441,970 E°cell = E°red (cathode) - E°red (anode) E°cell = -.76 - -3.05 E°cell = 2.29 ∆G° = -nFE°cell ∆G° = -(2)(96,500)(2.29) ∆G° = approx. -400,000 J (actual: -441,970)
Cu2+ (Ered = .34) and Cd2+ (Ered = -.40) are used to create a Galvanic Cell. What is the Standard Cell Potential (Ecell) in this case? (A) -.74 (B) -.06 (C) .06 (D) .74
(D) .74 E°cell = .34 - (-0.40) E°cell = .74
The total Voltage for a circuit with resistors in parallel is equal to 3.2 V. If R1 = 2.3 Ω, R2 = 6.5 Ω, and R3 = 9.7 Ω, what is the current that is going through R3 (I3)? (A) 3.29 (B) 1.33 (C) 2.04 (D) 0.33
(D) 0.33 V3 = Vt V3 = 3.2 V V3 = I3R3 3.2 = I3(9.7) I3 = 3.2 / 9.7 I3 = 0.33 C/s
A Test Charge (6.7⋅10^-14 C) is sitting 2.4⋅10^-3 meters away from a Source Charge (4.2⋅10^-12 C). What is the Electric Potential Energy (in J) between these two charges? (A) 4.55⋅10^-9 (B) 6.87⋅10^-10 (C) 2.23⋅10^-11 (D) 1.05⋅10^-12
(D) 1.05⋅10^-12 V = k (Q / r) V = (9⋅10^9) ((4.2⋅10^-12) / (2.4⋅10^-3)) V = (9⋅10^9) (approx. 2⋅10^-9 (actual: 1.75⋅10^-9)) V = approx. 18 (actual: 15.75) EPE / q = V EPE / 6.7⋅10^-14 = 18 EPE = 1⋅10^-12 J (actual: 1.05⋅10^-12)
A Test Charge (6.7⋅10^-14 C) is sitting 2.4⋅10^-3 meters away from a Source Charge. What is the Electrostatic Force (in N) between these two charges if the Voltage is equal to 4.3 V at that point? (A) 9.87⋅10^-12 (B) 4.32⋅10^-15 (C) 2.88⋅10^-13 (D) 1.20⋅10^-10
(D) 1.20⋅10^-10 EPE / q = V EPE / (6.7⋅10^-14) = 4.3 EPE = (6.7⋅10^-14) x (4.3) EPE = approx. 3⋅10^-13 J (actual: 2.881⋅10^-13) Fe = EPE / r Fe = (3⋅10^-13) / (2.4⋅10^-3) Fe = approx. 1⋅10^-10 N (actual: 1.20⋅10^-10)
A Test Charge (2.5⋅10^-16 C) is placed 2.4 meters from a Source Charge (7.8⋅10^-13 C). What is the strength of the Electric Field? (A) 7.89⋅10^-2 N/C (B) 3.22⋅10^-2 N/C (C) 6.75⋅10^-3 N/C (D) 1.22⋅10^-3 N/C
(D) 1.22⋅10^-3 N/m E = k (Q / r^2) E = (9⋅10^9)((7.8⋅10^-13) / (2.4^2)) E = (9⋅10^9)(approx. 1.5⋅10^-13 (actual: 1.35⋅10^-13)) E = approx. 1⋅10^-3 N/C (actual: 1.215⋅10^-3)
What is the resistance of a copper wire (ρ = 1.68⋅10^-8 Ω⋅m) that is 1.47 m long with a diameter of 3.8⋅10^-3 m? (A) 8.23⋅10^-11 (B) 9.86⋅10^-5 (C) 6.50⋅10^-6 (D) 1.29⋅10^-3
(D) 1.29⋅10^-3 A=πr^2 A=π(1.9⋅10^-3)^2 A= about 12⋅10^-6 (actual 11.34⋅10^-6) R = ρ(L/A) R = (1.68⋅10^-8)(1.47/11.34⋅10^-6) R = (1.68⋅10^-8)(approx. 1⋅10^5 (actual: 1.30⋅10^5)) R = approx. 1⋅10^-3 (actual: 1.29⋅10^-3)
A certain capacitor has an area of 3.54 m^2 and a distance between the plates of 5.72⋅10^-3 m. If the total energy produced by the Capacitor is 49.8 J, what is the Voltage across the plates of the capacitor (ε₀ = 8.84⋅10^-12)? (A) 6.75⋅10^8 (B) 3.24⋅10^-4 (C) 9.88⋅10^-4 (D) 1.35⋅10^4
(D) 1.35⋅10^4 C = ε₀ (A / d) C = (8.84⋅10^-12) (3.54^2/ 5.72⋅10^-3 ) C = (8.84⋅10^-12) (approx. 5⋅10^4 (actual: 6.19⋅10^4) C = approx. 5⋅10^-7 (actual: 5.47⋅10^-7) E = 1/2C(V^2) 49.8 J = 1/2(5.47⋅10^-7)(V^2) 99.6 J / (5.47⋅10^-7) = V^2 V^2 = approx. 2⋅10^8 (actual: 1.82⋅10^8) V = approx. 2⋅10^4 (actual: 1.35⋅10^4)
Johnny is hanging onto two wires. One of them connects to the ceiling forming a 30 degree angle with the ceiling. The other is connected to a wall and is perpendicular to that wall (see backside of notecard for a visual representation). Johnny weighs 750 N (he has been on a diet). What is the tension in the horizontal wire (in N)?
(D) 1299 Angle = 30 degrees Force downward = 750 N y axis tension in wire 1 = 750N tension in wire 1 = 750/sin(30) = 1500N tension in wire 2 = x axis tension in wire 1 = 1500cos(30) = 1299N
You add regular paper (k = 3.6) between two capacitor plates of a capacitor (C = 25.8) without removing the battery (V = 14.9). What will the charge be on a capacitor plate after addition of the paper? (A) 1.38 (B) 13.8 (C) 138 (D) 1380
(D) 1380 C' = kC C' = (3.6) (25.8) C' = approx. 90 (92.88) C = Q / V 92.88 = Q / 14.9 Q = approx. 1500 (1383.9)
If ∆G° = 441,970 J, what is the value of the Equilibrium Constant K? (A) 2.33⋅10^-26 (B) 6.78⋅10^-34 (C) 2.80⋅10^-56 (D) 3.36⋅10^-78
(D) 3.36⋅10^-78 ∆G° = -RTlnK 441,970 = -(8.314)(298)lnK lnK = - 441,970 / (approx. 2500 (actual: 2477.57)) lnK = approx. 200 (actual: 178.39) K = approx. 3⋅10^-78 (actual: 3.36⋅10^-78)
An object with a weight of 97.89 N is submerged in water, and has a net force of 46.57 N acting on it. What is the volume of the object? (A) 5.67⋅10^3 (B) 9.88⋅10^1 (C) 2.43⋅10^-1 (D) 4.75⋅10^-3
(D) 4.75⋅10^-3 Weight of object = 100 N Net force = 50 N Buoyant force = 50 N ρ of water= 1000kg/ m^3 Buoyant force = Vρg 46.57 = V (1000)(9.8) V = 4.9⋅10^-3 m^3 (actual: 4.75⋅10^-3 m^3)
When a capacitor remains connected to a battery, adding a dielectric will: I. Increase the voltage II. Increase the charge III. Increase the capacitance (A) I Only (B) III Only (C) I and III Only (D) II and III Only
(D) II and III Only A dielectric will increase the capacitance of a capacitor, which will allow more charge to build up on the capacitor. This is because the induced polarization within the dielectric will effectively cancel out the charges on the plates, making the voltage difference between the two plates smaller. The battery will then add more charge to the plates in order to once again make the voltages equal, leaving the voltage unchaged while increasing the number of charges on each plate.
In ______________, the positively charged nucleus cannot move around. In ______________, the negatively charged electrons cannot move around. (A) insulators, insulators (B) insulators, insulators and conductors (C) insulators and conductors, insulators and conductors (D) insulators and conductors, insulators
(D) insulators and conductors, insulators In insulators and conductors, the positively charged nucleus cannot move around. In insulators, the negatively charged electrons cannot move around.
The anode is ___________ charged in a Galvanic Cell. The anode is ___________ charged in an Electrolytic cell. (A) positively, positively (B) positively, negatively (C) negatively, negatively (D) negatively, positively
(D) negatively, positively The anode is negatively charged in a Galvanic Cell. The anode is positively charged in an Electrolytic cell.
Electrons and protons have ____________ absolute value of charge and __________ mass. (A) different, different (B) different, the same (C) the same, the same (D) the same, different
(D) the same, different Electrons and protons have the same absolute value of charge and different mass.
Determine the following quantities for a circuit with 3 resistors (20, 30, and 50 Ohms respectively) in series and 125 V 1)the equivalent resistance, 2)the total current from the power supply, 3)the current through each resistor, 4)the voltage drop across each resistor, and 5)the power dissipated in each resistor.
1) 50+20+30=100 Ohms R+R.. 2)V=IR, 125=100I, 125/100, 5/4, 1.25 A 3)In series Current is the SAME EVERYWHERE so still 1.25 A 4) V=IR, 1.25*20=25, 1.25*30=37.5, 1.25*50=62.5 5)P1 = V1 * I1 P1 = (25.0 V)(1.25 A) P1 = 31.250 W P2 = I2^2 * R2 P2 = (1.25 A)^2*(30 Ω) P2 = 46.875 W P3 = V3^2/R3 P3 = (62.5 V)^2/(50 Ω) P3 = 78.125 W
Determine the following quantities for a circuit in parallel with resistors 20 100 and 50...voltage 125 the equivalent resistance, the total current from the power supply, the current through each resistor, the voltage drop across each resistor, and the power dissipated in each resistor.
1)1/20+1/100+1/50=8/100=2/25=25/2=12.5 2)V=IR, 125=12.5*I, I=10A 3)125=20*I, 6.25A 125=100*I, 1.25A 125=50*I, 2.5A 4)Volts ARE THE SAME in parallel so all=125 5)P1 = V1 * I1 P1 = (125.0 V)(6.25 A) P1 = 781.25 W P2 = I2^2*R2 P2 = (1.25 A)^2(100 Ω) P2 = 156.25 W P3 = V3^2/R3 P3 = (125 V)^2/(50 Ω) P3 = 312.50 W
What equation can be used to calculate the total Capacitance for the Equivalent Capacitor when you have capacitors in series?
1/Ceq = 1/C1 + 1/C2.... + 1/Cn
Density of water with units?
1000 Kg/m^3 or 1g/cm^3
What is the density of water?
1000kg/m^3
1atm is equivalent to how many pascals?
1atm=103,000 Pa
A "Ground" is an infinite reservoir for electrons. What does that mean? Give an example.
A "Ground" is an infinite reservoir for electrons, which means that it can accept an infinite number of electrons. An example would be the earth.
What is a Dielectric? Why do we place Dielectrics between capacitor plates?
A Dielectric is a non-conducting (insulating) material. We place them between capacitor plates to prevent them from touching and increase the capacitance. If they did touch, they would no longer store charge but rather just be part of the circuit, allowing charge to flow through them.
Describe the function of a barometer. give the measurements at sea level and Give the measurement units and relate them to other similar units.
A barometer uses mercury in a tube flipped into a tub of mercury and how much stays in the tube shows the outside pressure. at sea level it is 760 mmHg. 760 mmHg=1 atm=760 torr
What is the difference between a conservative force and a non-conservative force?
A conservative force conserves mechanical energy, and because of this it doesn't matter what path it takes to calculate work, just the beginning and ending position. like a spring or gravity A non conservative force doesn't conserve mechanical energy, and the energy cannot be regained by reversing the process, because of this the path affects the work done. like friction and air resistance.
Ammeters vs. Voltmeters. Do they have high or low resistance? Why?
Ammeters have a VERY low resistance because they want to measure the current without changing it. Voltmeters have an EXTREMELY high resistance so that no current will go toward the Voltmeter, which would ruin our measurement of the voltage at the two points.
You accidentally hooked up an Ammeter in parallel instead of in series, causing it to break. Your university charges you 50 bucks to replace the Ammeter! :( What should you learn from this mistake?
Ammeters have a VERY low resistance; therefore, all the current will divert and flow through the Ammeter. You will now never forget this.
What is the equation for net torque?
Angular acceleration times the moment of inertia (alpha *I=Tnet)
If Johnny starts his car and floors it, he accelerates constantly until he reaches a velocity of 62.44 m/s, which takes about 46.7 seconds. How far does he travel in that time? (A) 326 (B) 867 (C) 1231 (D) 1458
Average velocity = (62.44 m/s + 0 m/s)/ 2 = approx. 30 m/s (actual 31.22 m/s) (Average Velocity) x (Time) = Displacement ((62.44 + 0)/ 2) x (46.7) = Displacement (31.22)(46.7) = Displacement Displacement = approx. 1500 (actual: 1457.97)
Boltzmann's constant is a replacement for R in the ideal gas law that uses N as number of molecules instead of number of moles (n): PV = NRT instead of PV = nRT. What is the value of Boltzmann's constant given that R = 8.31 J/ mol K?
Boltmann's constant = kB = R/Avagadro's number kB = 8.31 / (6.02 x 10^23) kB = 1.38 x 10^-23 J/K
What is the difference between work and moment when dealing with mechanical advantage?
Both work and moment are equal to distance times force, but with work the force is in the same direction as the distance, with moment the distance is perpendicular.
What is the equation for buoyancy force?
Buoyancy Force = Weight of liquid displaced (in N) = Vρg
What equation is used to determine the Capacitance of a capacitor based on the charge built up on it.
C = Q/V C = Capacitance Q = Charge stored on one plate of the capacitor V = Voltage difference across the capacitor
What is the equation for heat capacity (C) in terms of heat (Q)?
C = Q/ΔT
What is the equation for Capacitance in terms of its intrinsic characteristics?
C = ε₀ (A / d) C = Capacitance ε₀ = Permittivity of Dielectric (8.84⋅10^-12) A = Area of each plate d = Distance between the two plates
What equation do you use to calculate the new Capacitance of a capacitor upon addition of a dielectric?
C' = kC C' = New Capacitance C = Capacitance without Dielectric k = Dielectric Constant
That same 10L of gas at STP had 13kJ applied to it. What is the gas's new volume (in L)? (A) 13 (B) 0.013 (C) 10.13 (D) 0.0067
C) 10.13 W = PΔV so ΔV=W/P W= 13k= 1.3*10^4 J P= 101,325 Pa ΔV= (1.310^4)/(1.0110^5) ΔV= about 0.1 (exactly 0.13 L) New Volume = Vi + ΔV New Volume = 10 + 0.13 = 10.13 L
If there is 7.54*10^20 molecules of Neon gas at 451K, what is the total internal energy of the gas? (A) 0.0074 (B) 0.74 (C) 7.04 (D) 70.4
C) 7.04 Utotal = 3/2NkBT N= 7.54*10^20 molecules kB= 1.38 x 10^-23 J/K T= 451K Utotal= (3/2)(7.54*10^20)(1.38 x10^-23)(451) Utotal about 5 (Actual 7.04
What equation can be used to calculate the total Capacitance for the Equivalent Capacitor when you have capacitors in parallel?
Ceq = C1 + C2... + Cn
What is the difference between adhesion and cohesion?
Cohesion is the attraction of water molecules to other water molecules. Adhesion is the attraction of water molecules to other surfaces. This is the reason for surface tension and a meniscus in a test tube, adhesion also helps in capillary action where fluid is aided in transport by its connection to the walls (smaller tube in big vat the water goes up it)
What is the equation for Reynold's number: Critical Speed in terms of Coefficient of Viscosity?
Critical speed = (Rη)/(2ρr) R = Reynolds Number η = Coefficient of Viscosity ρ = Density r = radius of tube Critical speed is the velocity at which turbulence would occur in the fluid.
What is the oxidizing agent and what is the reducing agent in the following reaction? Cu2+ + Zn(s) -> Cu(s) + Zn2+
Cu2+ is the oxidizing agent because it oxidizes Zn(s), taking away its electrons. Zn(s) is the reducing agent because it reduces Cu2+ by giving it electrons.
Current is defined as the direction that the negative or positive charge flows?
Current is defined as the direction that positive charge would flow. Electrons are actually the thing that is moving. We simply define current as going in the opposite direction as the electrons, which is really strange.
What is the heat capacity of a monoatomic gas at constant Volume (Cv)? What is the heat capacity of a monoatomic gas at constant Pressure (Cp)?
Cv = 3/2nR (Heat capacity at constant volume) Cp = 5/2nR (Heat capacity at constant pressure) R = Gas constant (8.314 J/mol K)
What does the area under the curve represent in a velocity vs. time graph?
Displacement
What is the equation for displacement in terms of average velocity?
Displacement = (Average Velocity) x (Time) This comes from the equation defining average velocity, shown in the image.
What equation can be used to calculate the total amount of energy produced by a capacitor when it is discharged in terms of the capacitance?
E = 1/2C(V^2) E = Total Energy produced by Capacitor C = Capacitance V = Voltage difference between the two plates of a capacitor
What equation can be used to calculate the total amount of energy produced by a capacitor when it is discharged in terms of the charge built up on one of the capacitor plates?
E = Q(V/2) E = Total Energy produced by Capacitor Q = Charge on one plate of capacitor V = Voltage difference between the two plates of a capacitor
What equation can be used to relate E to the distance between two charges?
E = k (Q / r^2) E = Electric Field Strength Q = Source Charge r = Distance between Q and q
What equation can be used to relate Electric Potential Energy to Electric Potential?
EPE / q = V EPE = Electric Potential Energy q = Charge V = Electric Potential
The Nernst Equation allows us to relate E°cell to Ecell. Write out this equation.
Ecell = E°cell - (.0592 / n)logQ Q=M of anode/M of cathode
What is the difference between Electric Potential and Electric Potential Energy?
Electric Potential Energy is the amount of energy required to move a charge from one location to another (units = J). Electric Potential is the amount of energy required to move a charge from one location to another per unit charge (units = J/C).
What is Newton's first law of motion?
Every body persists in its state of being at rest or of moving uniformly straight forward except insofar as it is compelled to change its state by force (unbalanced force). a change to velocity
Explain why the equivalent capacitance in the case of a parallel arrangement is equal to the sum of the individual capacitors' capacitances.
Explain why the equivalent capacitance in the case of a parallel arrangement is equal to the sum of the individual capacitors' capacitances. (imagine all lined up on top of one another run together so distance is same but area is large)
What equation simplifies the relationship -nFE°cell = -RTlnK, allowing us to compare the E°cell
E°cell = (.0592 / n)logK
What equation can be used to determine the Standard Cell Potential for a Galvanic Cell?
E°cell = E°red (cathode) - E°red (anode) E°cell=(delta G)/-nF
What is the equation for Hooke's law (restorative force of a spring in terms of displacement)?
F = -kx F = Restorative force k = spring constant x = displacement
What equation will allow you to calculate the Magnetic Force on a charge in a magnetic field?
F = qvBsinθ F = Magnetic Force q = Charge v = Velocity of the charge B = External Magnetic Field (N*s/C*m=1 Tesla) θ = angle between the magnetic field and the velocity of the charge
What is the equation for Force of Viscosity in terms of depth and velocity?
F = η ((A v)/d) F = Force of Viscosity on an object η =Coefficient of Viscosity A = Area in contact with fluid v = velocity of object d = depth of fluid The units of viscosity are Pa*s
True or False? A charge is repelled from another charge. As the two charges get farther away from one another, they will move slower and slower.
False. A charge is repelled from another charge. As the two charges get farther away from one another, they will accelerate at a slower and slower rate due to the decreasing Electrostatic Force. Remember that Force is not directly related to velocity but rather acceleration.
True or False. It is possible for a certain particle with a charge of +9 C to split into two smaller particles with charges of +3 C and +5 C as long as 1 C of charge is converted into heat.
False. According to the Law of Conservation of Charge. Charge will always be conserved.
True or False? When you cut a magnet in half, you end up with a north magnet and a south magnet.
False. All magnets have both a north and south pole. Cutting a magnet in half would simply give you two smaller magnets, both having their own north and south pole.
True or False: When travelling in a circular path at a constant speed, there are no net forces acting upon an object.
False. Because the object is travelling in a circular path, there is a net force going radially inward, changing the velocity without changing sped. When travelling in a circular path at a constant speed, there are net forces acting upon an object going radially inward.
True or False? Charges move more slowly through a resistor than through the rest of the circuit.
False. Charges move at the same speed throughout the entire circuit. Adding a resistor will cause the entire circuit as a whole to have a slower current.
True or False? There are rare dielectric materials with Dielectric Constants less than 1 due to their weak ability to insulate.
False. Dielectric materials are defined to be non-conducting materials. As such, their Dielectric Constant must always be greater than 1.
True or False? Electric Field lines will point from the negatively-charged plate to the positively-charged plate since that is the direction that electrons would flow.
False. Electric Field lines will point from the positively-charged plate to the negatively-charged plate since that is the direction that protons would flow. Remember: Electric Field lines, current, etc. is all defined in terms of the behavior of how positive charge would flow if it could.
True or False? Plate A is parallel and opposite to Plate B. If Plate A is twice the thickness of Plate B, it will store twice as much charge.
False. No matter the size or shape of the plates, they will always store equal and opposite amounts of charge.
True or False. The plates charge this way because the positive terminal will send out protons to the plate it is attached to while the negative terminal will send out electrons to the plate it is attached to.
False. Protons do not move! The electrons from the plate attached to the positive terminal will be attracted to the positive terminal, sent through the battery, and then pushed away from the negative terminal to the plate attached to the negative terminal.
True or False? The Center of Mass is located at the very center of an object that has a mass.
False. The Center of Mass is located at the mean position of mass in a body or system. It is where gravity can be assumed to act on the object.
What equation can be used to relate Electric Field Strength (E) to Electrostatic Force (Fe)
Fe / q = E = kQ/d^2 Fe = Electrostatic Force q = Test Charge E = Electric Field Strength
What equation can be used to relate Electrostatic Force to Electric Potential Energy?
Fe = EPE/r (similar to F = mgh) or EPE=Fe*r (Fe=charge*electric field strength since E=Fe/q) Fe = Electrostatic Force EPE = Electric Potential Energy r = Radius between the two charges
Compare the Electrostatic Equations for F, E, EPE, and V.
Fe = k ((q1q2) / r^2) E= Fe / q E = kQ/d^2 Fe = EPE/r EPE=Fe*r EPE=kQq/r V=EPE/q V=kQ/r kQ/r=EPE/q Voltage=V2-V1
Coulomb's Law can be used to quantify the force between two charges. Write out this equation.
Fe = k ((q1q2) / r^2) Fe = Electrostatic Force k = Coulomb's Constant (9⋅10^9) q1 = Charge 1 q2 = Charge 2 r = Radius between q1 and q2
What is oxidized and what is reduced in the following chemical reaction? Fe2O3 + 3CO -> 2Fe(s) + 3CO2
Fe is reduced as it gains electrons. C is oxidized as it loses electrons, going from a +2 to a +4 oxidation state.
what is the acceleration needed to keep a pie in hand with a friction coefficient of .8?
Fgravity=m*9.8 Ffriction=.8*Fnormal .8*Fnormal=9.8*m Fnormal=12.25*m F=m*a 12.25*m=m*a 12.25m/s^2=a
What happens to flow rate as the length of the tubing increases?
Flow rate decreases
What is Newton's Third Law of Motion?
For every action there is an equal and opposite reaction, or the forces of two bodies on each other are equal and opposite in direction.
Match the following xyz-plane directions with their corresponding unit vectors. I. x II. y III. z (A)h^ (B)î (C)ĵ (D)k^
I (B) x: î II (C) y: ĵ III (D) z: k^ When adding A and B from the picture you can just add the number with each letter together (add all i's, all j's, and all k's)
What equation typifies the definition of Current (I)?
I = ΔQ / Δt I = Current ΔQ = Change in charge Δt = Change in time
Cu2+ has a E°red of +.34 V, much higher than Li+ (E°red = -3.05). What is the significance of one ion having a much greater Standard Reduction Potential?
If an ion has a higher E°red, it means that that ion is much more likely to be reduced. The E°red is like the desire of an ion to be reduced. The higher E°red, the greater the desire/likelihood of that ion getting reduced.
How does the critical speed change as the radius of the tube is increased?
It decreases
How does the critical speed change as the density of the fluid is increased?
It decreases (inverse)
Compare the process of Charge by Conduction to Charge by Induction.
In Charge by Conduction, you charge a neutral object by physically touching a negatively-charged object to it. In Charge by Induction a charge is induced by bringing a negatively charged object close to another object.
You put a negatively-charged balloon on a wall. If the wall is an insulator, then why does the balloon stick to the wall?
Insulators can still polarize temporarily. The electrons move slightly further from the balloon while the protons move slightly closer to the balloon, resulting in a partial-positive charge near the balloon.
What equation is used to relate the Current (I1, I2, etc) across all of the resistors to the total Current (It) of a circuit when resistors are in parallel?
It = I1 + I2... + In
What equation is used to relate the Current (I1, I2, etc) across all of the resistors to the total Current (It) of a circuit when resistors are in series?
It = I1 = I2 = In
If the Radius of the tube is doubled, by what factor does the flow rate V/t (Q) change and does it increase or decrease?
It will increase by a factor of 16 (Q=R^4)
What is the equation for rotational Kinetic Energy?
KErot=.5Iw^2 (Kinetic energy of rotation=1/2 * moment of inertia * angular velocity ^2)
What is the equation for kinetic energy in terms of velocity?
Kinetic Energy = (1/2)mv^2 m = mass v = velocity or Work=1/2mv^2 so F*d=1/2mv^2
Li- (E°red = -3.05) and Zn2+ (E°red = -.76). Which is more likely to be the oxidizing agent and which the reducing agent? Which will be the cathode and which the anode?
Li- will be the reducing agent and will be oxidized as the anode while the Zn2+ will be the oxidizing agent and be reduced as the cathode. Think of the number as the more negative the more badly it wants to give the electrons, the more positive the more they want to accept. -3 is more negative than -.7 so -3 will give and be oxidized.
What is the key difference then between a gas and a liquid?
Liquids are incompressible, while gases are compressible.
What is the equation for mechanical advantage in terms of force in and out?
MA = Fout/Fin Fin = Force in Fout = Force out MA = Mechanical Advantage
What is the equation for density?
Mass/Volume, kg/m^3
What is positive and what is negative for torque?
Negative is clockwise counterclockwise is positive
If a box on an inclined plane is held stationary by friction, and the parallel component to the force of gravity has a force of 10 N, what is the force of friction?
Net force = 0 Force of friction- parallel force of gravity = 0 Force of friction = parallel force of gravity = 10 N
What is Bernoulli's equation in terms of pressure, height, and velocity of a fluid at two points in a pipe?
P1 + 1/2ρv1^2 + ρgh1 = P2 + 1/2ρv2^2 + ρgh2 P1 = Pressure at Point 1 (Pa) P2 = Pressure at Point 2 (Pa) ρ = Density of the Fluid (kg/m^3) v1 = Velocity at Point 1 (m/s) v2 = Velocity at Point 2 (m/s) g = Acceleration due to Gravity (9.8m/s^2) h1 = Height at Point 1 (m) h2 = Height at Point 2 (m) Another way to look at this is as Wi + PEi + KEi = Wo + PEo + KEo, where i is for input and o is for output
Boyles law?
P1V1=P2V2
Remembering the equation for pressure, What are the units for a pascal? How many pascals are in an atm?
P=F/A Pa=N/m^2 101,325 Pa=1 atm
What is the formula for pressure?
P=F/A (pressure=Force/Area)
What is the equation for the potential energy of a spring or work done by a spring?
PEs = 1/2 k x^2 PEs = Potential energy of a spring x = displacement k = spring constant
What is the ideal gas law (relationship of pressure, volume, temperature and moles of a gas)?
PV = nRT P = Pressure (Pascals) V = Volume (m^3) n = Number of Moles (moles) R = Gas Constant (8.314 J/K*mol) (.082 L*atm/K*mol) T = Absolute Temperature (K) Remember the assumptions of no intermolecular forces, no volume for gas particles (cloud has no volume/shape) and that all collisions are perfectly elastic, KE>PE
What is Dalton's Law of Partial Pressures, used to determine how much pressure of a mix of gases is caused by one of the gaseous components?
Pa = Xa x Pt Pa = Partial Pressure of one gas Xa = mole fraction of that gas Pt = Total Pressure
If a car is moving 28.76 m/s and the engine is applying a force of 114.89 N, what is the power output of the engine at that moment (in W)? (A) 2164.32 (B) 2597.65 (C) 3304.24 (D) 4587.92
Power = Force x Velocity Power = (114.89)(28.76) Power = approx. 3000 J/s (actual: 3304.24)
What is Pascal's principle (relationship between pressure in and pressure out)? How do the forces in and out relate to this concept?
Pressure in = Pressure out Because of this, the forces are related to the area: F1/A1 = F2/A2 = Pressure in = Pressure out
What is the equation for Poiseuille's Law: Flow Rate in terms of Pressure Gradient?
Q = (∆Pπr^4)/(8ηL) Q = V/t = Volume/time = Flow Rate (m^3/s) r = Radius of Tubing (m) ∆P = Pressure Gradient (Pa) η = Coefficient of Viscosity (Pa·s, or kg/s·m) L = Length of Tubing (m)
What equation relates flow rate (Q) to velocity and area?
Q = velocity x Area
What equation is used to determine the Resistance of a resistor based on its intrinsic properties?
R = ρ(L/A) R = Resistance ρ = Resistivity (ohms*meter) L = Length A = Area (HINT: REPLAY)
If a rigid container has 1 mole of gas in it, and the pressure is increased by adding more gas from 101,325 Pa to 303,975 Pa, how much gas was added (in moles)? (A) 1 (B) 2 (C) 3 (D) 4
Rearrange Ideal gas law: R =PV/nT P1V1/n1T1 = P2V2/n2T2 Volume and temperature are held constant, so P1/n1 = P2/n2 101,325/1 = 303,975/n2 n2 = 3 mol Amount added = n2-n1 = 2 mol
What happens to resistance as the area of the resistor is increased? Why?
Resistance will decrease as area increases due to the increased number of paths that the electrons can take through the resistive material.
What happens to resistance as the length of the resistor is increased? Why?
Resistance will increase as length increases due to the longer amount of time that the electrons will need to travel through resistive material.
What equation is used to relate the Resistance (R1, R2, etc) across all of the resistors to the total Resistance (Rt) of a circuit when resistors are in series?
Rt = R1 + R2... + Rn
What is STP (standard temperature and pressure), and molar volume at STP?
STP = 273 K or 0 C, 101,325 Pa (1 atm) 1 mol at STP = 22.4 L = .0224 m^3
What is the equation for specific gravity? How does this relate to the percent of an object that will be below the surface if floating in water?
Specific Gravity = (ρ of object)/(ρ of water) Specific gravity = percent of object below water when floating.
How do you add two vectors?
Tail to head and draw the resulting triangle. A+B=C vectors
Compare Source Charge (Q) and Test Charge (q).
The Source Charge (Q) is the charge that is generating the Electric Field. The Test Charge (q) is the charge that is being used to determine the strength and direction of the Electric Field.
Van der Waals equation can be represented as: [P0 + a(n/V)^2](Vc - nb) = nRT What is the difference between this and the ideal gas law (PV = nRT)? Why do we need this equation?
The Van der Waals takes into account two adjustments for the non-ideal behavior of real gases. Because the molecules of real gases take up space and have intermolecular interactions, pressure and volume need to be adjusted. This is where the a (attraction constant) and b (bigness constant) terms come from.
What is the average velocity if acceleration is constant?
Va=(Vf+Vi)/2 ONLY if Constant acceleration
The closer a similarly charged Test Charge is to a Source Charge, the higher or lower the Electric Potential? Why?
The closer the Test Charge is to the Source Charge, the higher the Electric Potential. This is because the charges will move away from each other (essentially decreasing their potential for generating kinetic energy from their Electric Potential).
What is the equation for the definition of acceleration and the displacement curve?
The first and last
You have two of the same scenario with a ball on the ground. In The first the forces are gravity on the ball and the earth on the ball. The second are the earth on the ball and the ball on the earth. What laws of motion apply?
The first scenario is the first law of motion since both are on one object and the second is the third law of motion because there are two objects receiving force action reaction.
Pressure is added to one part of a liquid system. according to pascals principle what happens to the rest?
The force is distributed evenly throughout the fluid.
As depth of fluid increases, what happens to the force of viscosity?
The force of viscosity decreases
As velocity of object increases, what happens to the force of viscosity?
The force of viscosity increases.
One point is closer to the axis of rotation, another is further away. Which has the higher moment of inertia?
The further away you go the higher the moment of inertia gets.
What does the slope at a point on a position vs time graph represent?
The instantaneous velocity at that point.
How is the strength of an electric field depicted in a diagram with electric field lines?
The more lines in a given area, the stronger the electric field is implied to be.
The north pole of a magnet would be attracted to the north or south pole of another magnet?
The north pole of a magnet would be attracted to the south pole of another magnet.
What will happen if a force acts on an object, but not on its center of mass?
The object will rotate around the center of mass. creating torque
What is the purpose of a salt bridge?
The purpose of a salt bridge is to neutralize the charges in the solutions that are either becoming positive or negative as the reaction proceeds. This allows the reaction to continue moving forward.
The Electrolytic Resistivity refers to what?
The resistivity of a liquid that can conduct electricity.
Why is the voltage across each capacitor exactly the same for each capacitor in a parallel configuration?
The voltage across each capacitor is exactly the same as the overall voltage because each capacitor is directly linked to the battery and every spot along a wire that isn't interrupted by either a resistor or a capacitor will have the exact same voltage in it.
Why is the Equivalent capacitance less than the capacitance for each individual capacitor when in series?
Think about it as if you were to add the distances together when creating the large one capacitor. This would decrease the overall capacitance.
Why do high jumpers arch their backs as they jump over the bar?
This allows their center of mass to be lower than the bar. The center of mass is actually outside their body!
Explain why the charge on all the capacitors in series must be equal to each other?
This is because for each electron that moves from one plate to another plate, it will cause a chain reaction, resulting in one electron building up on each plate.
True or False? An object being acted on by an unbalanced Force will accelerate.
True
What does it mean to say that a capacitor has a high amount of Capacitance?
To say a capacitor has a high Capacitance is to say that it is very good at storing charge.
Zn2+ has a Standard Reduction Potential (E°red) of -.76 V. What does that mean?
To say that Zn2+ has a Ered of -.76 V is to say that the reduction of Zn2+ has a voltage difference that is .76 V below the reference value, which is the reduction of H+.
Define Torque and give the equation and units.
Torque is a force applied a distance away from the center of mass causing rotation. T=F*d (torque equals force perpendicular to the object or distance vector * distance from the center of mass) the units are Nm (N*meters)
True or false: Even though the calculation of static friction [(coefficient of static friction)·(normal force)]could exceed the other forces acting on an object, static friction will not cause an object to accelerate.
True. Even though the calculation of static friction [(coefficient of static friction)·(normal force)] could exceed the other forces acting on an object, static friction will not cause an object to accelerate. Remember, this is STATIC friction. At its strongest, it only keeps position the same, not cause acceleration!
True or False? It is possible for a certain particle with a charge of 0 C to split into two smaller particles with charges of +3 C and -3 C.
True. It is possible for a certain particle with a charge of 0 C to split into two smaller particles with charges of +3 C and -3 C. The overall charge was preserved.
What is the total internal energy (kinetic energy) of a mono-atomic gas (Utotal) in terms of Volume (V), number of molecules (N), and number of moles (n)?
Utotal = 3/2PV = 3/2NkBT = 3/2nRT Utotal = Total energy of mono-atomic gas P = Pressure V = Volume N = Number of molecules kB = Boltzmann's constant (1.38 x 10^-23 J/K) T = Temperature n = Number of moles R = Gas constant (8.314 J/mol K) (basically all versions of the ideal gas law PV=nRT or PV=NkBT with a 3/2 in front)
Ohm's Law is used to relate the Current to the Resistance. Write out this equation.
V = IR V = Voltage I = Current R = Resistance
What equation is used to relate Electric Potential (V) to the Source Charge (Q)?
V = k (Q / r) V = Electric Potential k = Coulomb's Constant (9⋅10^9) Q = Source Charge r = Radius between Q and q
Charles Law?
V1/T1=V2/T2
Avagadro Law?
V1/n1=V2/n2
What is the difference between vectors and scalars? Which is distance? Which is Displacement? Speed? Time? Velocity? Force? Mass? Temperature? Acceleration?
Vector:Magnitude/size and DIRECTION Scalar:ONLY magnitude/size Displacement, velocity, acceleration, force is a vector-has direction Distance, speed, time, mass, temperature is a scalar-only has quantity
What's the difference between Electric Potential and Voltage?
Voltage (ΔV) refers to a difference in Electric Potential (V) between two points.
What equation is used to relate the Voltage drops (V1, V2, etc) across all of the resistors to the total Voltage (Vt) of a circuit when resistors are in series?
Vt = V1 + V2... + Vn
What equation is used to relate the Voltage drops (V1, V2, etc) across all of the resistors to the total Voltage (Vt) of a circuit when resistors are in parallel?
Vt = V1 = V2 = Vn
Your professor makes an analogy comparing centripetal force to magnetic force. How are these two concepts related?
When magnetic force acts on a charge, it causes it to change directions in a way that makes it go in a circle
Consider the following Galvanic Cell: https://fthmb.tqn.com/YUma5BLsDaaZLT7X3iw5SureRVY=/735x0/battery-56a128375f9b58b7d0bc8c92.gif Write out the shorthand notation for this galvanic cell.
Zn(s) | Zn2+ || Cu2+ | Cu
You rub a balloon against your head and then hold it near your head. Considering that the balloon became negatively charged, what about your hair makes it attracted to the balloon, causing it to stand up?
When the balloon is brought close to your head, the negatively-charged balloon repels the electrons in your hair, sending them down closer to your head, making the ends of your hair positively-charged, resulting in its attraction to the balloon.
What is the venturi effect?
When there is a constriction in a tube, the velocity of the fluid will increase at that point while the pressure will be lower.
What is the equation for power in terms of work or average power? instantaneous power?
average Power = Work / Time instantaneous power=Fv
Give a real life example of the Triboelectric Effect.
When you rub your feet on a carpet and charge builds up on your body.
What is the equation for work in terms of force?
Work = Force x Distance
What is the equation for Work in terms of Volume at constant pressure?
Work = Pressure x Change in Volume
What is the Work-Energy principle? (Work in terms of Kinetic energy)
Work = change in kinetic energy
Why is the charge of an electron considered the "Fundamental Unit of Charge"?
You cannot divide an electron and therefore the charge of an electron is the smallest possible unit of charge; thus, we refer to it as the "Fundamental Unit of Charge"
Describe how you could use a capacitor to light a lightbulb (a resistor).
You could charge up the capacitor using a battery and then hook up the lightbulb to the circuit. Electrons would then flow from the negatively-charged plate to the positively-charged plate, creating a current that would light the lightbulb.
(i) Using Van der Waals equation, calculate the temperature of 20.0 mole of helium in a 10.0 litre cylinder at 120 atmosphere pressure. [Data - Van der Waals constants for helium: a = 0.0341 L2 at mol-2; b = 0.0237 L mol-1]
[P0+a(n/V)^2](Vc-nb)=nRT [120+.0341(20/10)^2](10-20*.0237)=20*.082*T T=696K
What is the equation that relates the forces in and out when dealing with mechanical advantage in terms of distance of forces from a fulcrum?
f1 x d1 = f2 x d2 F1 = force 1 d1 = distance from force 1 to fulcrum f2 = force 2 d2 = distance from force 2 to fulcrum
Illustrate how induction using a Ground could result in a neutral metal ball becoming negatively charged.
just switch the - and + symbols. positive charge gets close, neutral is polarized and positives leave to ground and bring in -.
What is the equation for kinetic friction in terms of normal force?
kinetic friction ≤ (coefficient of kinetic friction)·(normal force)
Draw all of the force components of a block on an inclined plane. finding the x and y components of force of gravity (hint triangle with force of gravity)
mgsintheta=vector going with plane mgcos=vector
Give the equations for angular (L) and linear momentum (p).
p=m*v L=I*w (always conserved)
When will work be positive and negative?
positive gives energy (pushing skateboarder) negative energy takes energy (stopping skateboarder)
What is the purpose of a Capacitor?
store charge
What is the equation of continuity? What is the purpose of this equation?
v1A1 = v2A2 v1 = velocity in A1 = area in v2 = velocity out A2 = Area out Compares flow of fluid in a pipe of varying cross sectional area.
Convert 68° Fahrenheit to both Celsius and Kelvin
°F = (°C)(9/5) + 32 68°F= (°C) (9/5) +32 36*5/9= (°C) (°C)=20 K = (°C) + 273.15 K = 20 + 273.15= 293.15
What is the conversion between Fahrenheit and Celsius, and Celsius and Kelvin?
°F = (°C)(9/5) + 32 <- don't worry about memorizing this. K = (°C) + 273.15
What is change in internal energy (ΔU) in terms of heat (Q) and work (W)?
ΔU = Q + W ΔU = change in internal energy Q = heat put into system W = work done to system
How are Resistivity (ρ) and Conductivity (σ) related?
ρ = 1/σ σ=1/ρ the better the conductor the worse the resistor and vice versa
What equation allows you to calculate the Gibb's Free Energy for a Galvanic Cell based on the Cell Potential (Ecell)?
∆G = -nFEcell ∆G = Gibb's Free Energy n = Number of Electrons F = 96,500 C/mol (1.6*10^-19 C/e-) Ecell = Cell Potential (E cathode-E anode)
What equation allows you to calculate the Standard Gibb's Free Energy for a Galvanterm-232ic Cell based on the Standard Cell Potential (E°cell)?
∆G° = -nFE°cell ∆G° = Standard Gibb's Free Energy n = Number of Electrons F = 96,500 C/mol E°cell = Standard Cell Potential (1.1V)
