2008BAP 2 - AP® Physics B 2008 Free-Response Questions...

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Unformatted text preview: AP® Physics B 2008 Free-Response Questions Form B The College Board: Connecting Students to College Success The College Board is a not-for-profit membership association whose mission is to connect students to college success and opportunity. Founded in 1900, the association is composed of more than 5,000 schools, colleges, universities, and other educational organizations. Each year, the College Board serves seven million students and their parents, 23,000 high schools, and 3,500 colleges through major programs and services in college admissions, guidance, assessment, financial aid, enrollment, and teaching and learning. Among its best-known programs are the SAT®, the PSAT/NMSQT®, and the Advanced Placement Program® (AP®). The College Board is committed to the principles of excellence and equity, and that commitment is embodied in all of its programs, services, activities, and concerns. © 2008 The College Board. All rights reserved. College Board, Advanced Placement Program, AP, AP Central, SAT, and the acorn logo are registered trademarks of the College Board. PSAT/NMSQT is a registered trademark of the College Board and National Merit Scholarship Corporation. Permission to use copyrighted College Board materials may be requested online at: www.collegeboard.com/inquiry/cbpermit.html. Visit the College Board on the Web: www.collegeboard.com. AP Central is the official online home for the AP Program: apcentral.collegeboard.com. TABLE OF INFORMATION FOR 2008 and 2009 CONSTANTS AND CONVERSION FACTORS Proton mass, m p Neutron mass, mn Electron mass, me Avogadro’s number, N 0 Universal gas constant, 1.67 1.67 10 10 27 27 31 kg kg kg Electron charge magnitude, e 1.60 10 19 C 1 electron volt, 1 eV Speed of light, Universal gravitational constant, Acceleration due to gravity at Earth’s surface, 1.60 10 19 J 9.11 10 6.02 c G 3.00 6.67 108 m s 10 11 1023 mol -1 m 3 kg s2 R 8.31 J (mol K) 1.38 10 23 g 9.8 m s2 Boltzmann’s constant, k B JK 1u h hc 1 unified atomic mass unit, Planck’s constant, Vacuum permittivity, Coulomb’s law constant, k Vacuum permeability, Magnetic constant, k 1 atmosphere pressure, meter, kilogram, second, ampere, kelvin, m kg s A K mole, hertz, newton, pascal, joule, mol Hz N Pa J 1.66 6.63 1.99 8.85 9.0 4p 10 7 10 10 10 10 27 34 25 12 kg Js Jm 2 931 MeV c 2 4.14 1.24 2 10 15 3 eV s 10 eV nm 0 C Nm 1 4p 0 109 N m 2 C2 10 7 m0 m0 4 p (T m) A (T m) A 1 atm 1.0 105 N m 2 W C V W H 1.0 105 Pa F T C eV UNIT SYMBOLS watt, coulomb, volt, ohm, henry, farad, tesla, degree Celsius, electron-volt, PREFIXES Factor 10 9 106 103 10 2 10 3 VALUES OF TRIGONOMETRIC FUNCTIONS FOR COMMON ANGLES Symbol G M k c m Prefix giga mega kilo centi milli micro nano pico q sin q cos q tan q 0 30 37 45 53 60 90 0 1 0 12 32 33 35 45 34 22 22 1 45 35 43 32 1 0 12 3 10 6 10 9 10 12 m n p The following conventions are used in this exam. I. Unless otherwise stated, the frame of reference of any problem is assumed to be inertial. II. The direction of any electric current is the direction of flow of positive charge (conventional current). III. For any isolated electric charge, the electric potential is defined as zero at an infinite distance from the charge. IV. For mechanics and thermodynamics equations, W represents the work done on a system. -2- ADVANCED PLACEMENT PHYSICS B EQUATIONS FOR 2008 and 2009 NEWTONIAN MECHANICS ELECTRICITY AND MAGNETISM u u0 at x x0 u0 t 12 at 2 x0 u2 u0 2 2a x F Ffric ac Fnet mN u2 r rF sin q ma a F f h J K k m N P p r T t U u W x m q t t p J K mv FDt 12 mu 2 mgh F Dr cos q W Dt Dp DUg W Pavg = = = = = = = = = = = = = = = = = = = = = = acceleration force frequency height impulse kinetic energy spring constant length mass normal force power momentum radius or distance period time potential energy velocity or speed work done on a system position coefficient of friction angle torque F E 1 q1q2 4p 0 r 2 F q A B C d E F I UE Eavg V C C Uc I avg qV V d 1 4p 0 Q V 0A 1 q1q2 4p 0 r e i qi ri d 1 QV 2 1 CV 2 2 P Q q R r t U V = = = = = = = = = = = = = = = = = DQ Dt R V P Cp 1 Cs Rs r A IR IV i u= r= q= fm = area magnetic field capacitance distance electric field emf force current length power charge point charge resistance distance time potential (stored) energy electric potential or potential difference velocity or speed resistivity angle magnetic flux P Fs F u cos q kx 12 kx 2 Ci Us 1 i Ci i Ri Ts Tp 2p 2p m k g 1 Rp FB FB B i 1 Ri qu B sin q BI sin q m0 I 2p r BA cos q T 1 f Gm1m2 r2 FG fm UG Gm1m2 r eavg Dfm Dt Bu e -3- ADVANCED PLACEMENT PHYSICS B EQUATIONS FOR 2008 and 2009 FLUID MECHANICS AND THERMAL PHYSICS WAVES AND OPTICS P Fbuoy P0 rgh rVg A1u1 P D A2 u2 rgy a 12 ru 2 0 DT const. H P kA DT L F A PV K avg nRT 3 kT 2B Nk BT urms 3 RT M 3k B T m W DU P DV Q W e W QH TH TH TC A = area e = efficiency F = force h = depth H = rate of heat transfer k = thermal conductivity K avg =average molecular kinetic energy = length L = thickness M = molar mass n = number of moles N = number of molecules P = pressure Q = heat transferred to a system T = temperature U = internal energy V = volume u = velocity or speed urms =root-mean-square velocity W = work done on a system y = height a = coefficient of linear expansion m = mass of molecule r = density u n fl c u n 1 sin q1 sin qc 1 si 1 s0 n 2 sin q2 n2 n1 1 f M f hi h0 si s0 R 2 d sin q ml m lL d d = separation f = frequency or focal length h = height L = distance M = magnification m = an integer n = index of refraction R = radius of curvature s = distance u = speed x = position l = wavelength q = angle xm GEOMETRY AND TRIGONOMETRY Rectangle A bh Triangle 1 A bh 2 Circle A pr 2 C 2pr Parallelepiped V wh Cylinder V pr 2 A= C= V= S= b= h= = w= r= area circumference volume surface area base height length width radius ec ATOMIC AND NUCLEAR PHYSICS E hf hf pc K max f l h p DE ( Dm ) c 2 E = energy f = frequency K = kinetic energy m = mass p = momentum l = wavelength f = work function S 2pr 2pr 2 Sphere 43 V pr 3 S 4pr 2 Right Triangle a 2 b2 c2 a sin q c b cos q c a tan q b c q b 90 a -4- 2008 AP® PHYSICS B FREE-RESPONSE QUESTIONS (Form B) PHYSICS B SECTION II Time— 90 minutes 7 Questions Directions: Answer all seven questions, which are weighted according to the points indicated. The suggested times are about 11 minutes for answering Questions 1 and 4-7 and about 17 minutes for answering each of Questions 2 and 3. The parts within a question may not have equal weight. Show all your work in the goldenrod booklet in the spaces provided after each part, NOT in this lavender insert. 1. (10 points) A 70 kg woman and her 35 kg son are standing at rest on an ice rink, as shown above. They push against each other for a time of 0.60 s, causing them to glide apart. The speed of the woman immediately after they separate is 0.55 m s . Assume that during the push, friction is negligible compared with the forces the people exert on each other. (a) Calculate the initial speed of the son after the push. (b) Calculate the magnitude of the average force exerted on the son by the mother during the push. (c) How do the magnitude and direction of the average force exerted on the mother by the son during the push compare with those of the average force exerted on the son by the mother? Justify your answer. (d) After the initial push, the friction that the ice exerts cannot be considered negligible, and the mother comes to rest after moving a distance of 7.0 m across the ice. If their coefficients of friction are the same, how far does the son move after the push? © 2008 The College Board. All rights reserved. Visit apcentral.collegeboard.com (for AP professionals) and www.collegeboard.com/apstudents (for students and parents). GO ON TO THE NEXT PAGE. -5- 2008 AP® PHYSICS B FREE-RESPONSE QUESTIONS (Form B) 2. (15 points) A 4700 kg truck carrying a 900 kg crate is traveling at 25 m/s to the right along a straight, level highway, as shown above. The truck driver then applies the brakes, and as it slows down, the truck travels 55 m in the next 3.0 s. The crate does not slide on the back of the truck. (a) Calculate the magnitude of the acceleration of the truck, assuming it is constant. (b) On the diagram below, draw and label all the forces acting on the crate during braking. (c) i. Calculate the minimum coefficient of friction between the crate and truck that prevents the crate from sliding. ii. Indicate whether this friction is static or kinetic. ____ Static ____Kinetic Now assume the bed of the truck is frictionless, but there is a spring of spring constant 9200 N m attaching the crate to the truck, as shown below. The truck is initially at rest. (d) If the truck and crate have the same acceleration, calculate the extension of the spring as the truck accelerates from rest to 25 m s in 10 s. (e) At some later time, the truck is moving at a constant speed of 25 m s and the crate is in equilibrium. Indicate whether the extension of the spring is greater than, less than, or the same as in part (d) when the truck was accelerating. ___ Greater Explain your reasoning. ___ Less ___ The same © 2008 The College Board. All rights reserved. Visit apcentral.collegeboard.com (for AP professionals) and www.collegeboard.com/apstudents (for students and parents). GO ON TO THE NEXT PAGE. -6- 2008 AP® PHYSICS B FREE-RESPONSE QUESTIONS (Form B) 3. (15 points) A student is measuring the magnetic field generated by a long, straight wire carrying a constant current. A magnetic field probe is held at various distances d from the wire, as shown above, and the magnetic field is measured. The graph below shows the five data points the student measured and a best-fit curve for the data. Unfortunately, the student forgot about Earth’s magnetic field, which has a value of 5.0 10 5 T at this location and is directed north. (a) On the graph, plot new points for the field due only to the wire. (b) Calculate the value of the current in the wire. © 2008 The College Board. All rights reserved. Visit apcentral.collegeboard.com (for AP professionals) and www.collegeboard.com/apstudents (for students and parents). GO ON TO THE NEXT PAGE. -7- 2008 AP® PHYSICS B FREE-RESPONSE QUESTIONS (Form B) Another student, who does not have a magnetic field probe, uses a compass and the known value of Earth’s magnetic field to determine the magnetic field generated by the wire. With the current turned off, the student places the compass 0.040 m from the wire, and the compass points directly toward the wire as shown below. The student then turns on a 35 A current directed into the page. (c) On the compass, sketch the general direction the needle points after the current is established. (d) Calculate how many degrees the compass needle rotates from its initial position pointing directly north. The wire is part of a circuit containing a power source with an emf of 120 V and negligible internal resistance. (e) Calculate the total resistance of the circuit. (f) Calculate the rate at which energy is dissipated in the circuit. © 2008 The College Board. All rights reserved. Visit apcentral.collegeboard.com (for AP professionals) and www.collegeboard.com/apstudents (for students and parents). GO ON TO THE NEXT PAGE. -8- 2008 AP® PHYSICS B FREE-RESPONSE QUESTIONS (Form B) 4. (10 points) A fountain with an opening of radius 0.015 m shoots a stream of water vertically from ground level at 6.0 m/s . The density of water is 1000 kg m3 . (a) Calculate the volume rate of flow of water. (b) The fountain is fed by a pipe that at one point has a radius of 0.025 m and is 2.5 m below the fountain’s opening. Calculate the absolute pressure in the pipe at this point. (c) The fountain owner wants to launch the water 4.0 m into the air with the same volume flow rate. A nozzle can be attached to change the size of the opening. Calculate the radius needed on this new nozzle. © 2008 The College Board. All rights reserved. Visit apcentral.collegeboard.com (for AP professionals) and www.collegeboard.com/apstudents (for students and parents). GO ON TO THE NEXT PAGE. -9- 2008 AP® PHYSICS B FREE-RESPONSE QUESTIONS (Form B) 5. (10 points) A thin converging lens L of focal length 10.0 cm is used as a simple magnifier to examine an object O that is placed 6.0 cm from the lens. (a) On the figure below, draw a ray diagram showing at least two incident rays and the position and size of the image formed. (b) i. Indicate whether the image is real or virtual. ____ Real ____ Virtual ii. Justify your answer. (c) Calculate the distance of the image from the center of the lens. (Do NOT simply measure your ray diagram.) (d) The object is now moved 3.0 cm to the right, as shown above. How does the height of the new image compare with that of the previous image? ____ It is larger. Justify your answer. ____ It is smaller. ____ It is the same size. © 2008 The College Board. All rights reserved. Visit apcentral.collegeboard.com (for AP professionals) and www.collegeboard.com/apstudents (for students and parents). GO ON TO THE NEXT PAGE. -10- 2008 AP® PHYSICS B FREE-RESPONSE QUESTIONS (Form B) 6. (10 points) A 0.0040 mol sample of a monatomic gas is taken through the cycle shown above. The temperature T1 of state 1 is 300 K. (a) Calculate T2 and T3 . (b) Calculate the amount of work done on the gas in one cycle. (c) Is the net work done on the gas in one complete cycle positive, negative, or zero? ____ Positive ____ Negative ____ Zero (d) Calculate the heat added to the gas during process 1 2. © 2008 The College Board. All rights reserved. Visit apcentral.collegeboard.com (for AP professionals) and www.collegeboard.com/apstudents (for students and parents). GO ON TO THE NEXT PAGE. -11- 2008 AP® PHYSICS B FREE-RESPONSE QUESTIONS (Form B) 7. (10 points) Following a nuclear reaction, a nucleus of aluminum is at rest in an excited state represented by above left. The excited nucleus returns to the ground state 27 13 Al 27 13 Al* , as shown by emitting a gamma ray photon of energy 1.02 MeV, as shown above right. The aluminum nucleus in the ground state has a mass of 4.48 Assume nonrelativistic equations apply to the motion of the nucleus. (a) Calculate the wavelength of the emitted photon in meters. (b) Calculate the momentum of the emitted photon in kg m s . (c) Calculate the speed of the recoiling nucleus in m s . (d) Calculate the kinetic energy of the recoiling nucleus in joules. 10 26 kg . END OF EXAM © 2008 The College Board. All rights reserved. Visit apcentral.collegeboard.com (for AP professionals) and www.collegeboard.com/apstudents (for students and parents). -12- ...
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This note was uploaded on 02/09/2011 for the course PHYS 10 taught by Professor Davidnewton during the Spring '11 term at DeAnza College.

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