AP Physics B 1979 Free Response Questions

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1 AP Physics B 1979 Free Response Questions The materials included in these files are intended for use by AP teachers for course and exam preparation in the classroom; permission for any other use must be sought from the Advanced Placement Program. Teachers may reproduce them, in whole or in part, in limited quantities, for face-to-face teaching purposes but may not mass distribute the materials, electronically or otherwise. These materials and any copies made of them may not be resold, and the copyright notices must be retained as they appear here. This permission does not apply to any third-party copyrights contained herein. These materials were produced by Educational Testing Service (ETS ), which develops and administers the examinations of the Advanced Placement Program for the College Board. The College Board and Educational Testing Service (ETS) are dedicated to the principle of equal opportunity, and their programs, services, and employment policies are guided by that principle. The College Board is a national nonprofit membership association dedicated to preparing, inspiring, and connecting students to college and opportunity. Founded in 1900, the association is composed of more than 4,200 schools, colleges, universities, and other educational organizations. Each year, the College Board serves over three million students and their parents, 22,000 high schools, and 3,500 colleges, through major programs and services in college admission, 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 equity and excellence, and that commitment is embodied in all of its programs, services, activities, and concerns. APIEL is a trademark owned by the College Entrance Examination Board. PSAT/NMSQT is a registered trademark jointly owned by the College Entrance Examination Board and the National Merit Scholarship Corporation. Educational Testing Service and ETS are registered trademarks of Educational Testing Service.

2 1979B1. From the top of a cliff 80 meters high, a ball of mass 0.4 kilogram is launched horizontally with a velocity of 30 meters per second at time t = 0 as shown above. The potential energy of the ball is zero at the bottom of the cliff. Use g = 10 meters per second squared. a. Calculate the potential, kinetic, and total energies of the ball at time t = O. b. On the axes below, sketch and Label graphs of the potential, kinetic, and total energies of the ball as functions of the distance fallen from the top of the cliff cliff cliff c. On the axes below sketch and label the kinetic and potential energies of the ball as functions of time until the ball hits

3 1979B2. A 10-kilogram block rests initially on a table as shown in cases I and II above. The coefficient of sliding friction between the block and the table is 0.2. The block is connected to a cord of negligible mass, which hangs over a massless frictionless pulley. In case I a force of 50 newtons is applied to the cord. In case II an object of mass 5 kilograms is hung on the bottom of the cord. Use g = 10 meters per second squared. a. Calculate the acceleration of the 10-kilogram block in case I. b. On the diagrams below, draw and label all the forces acting on each block in case II 10 kg 5 kg c. Calculate the acceleration of the 10-kilogram block in case II. 1979B3. A group of muons is observed to pass a balloon at a height of 480 meters above the Earth's surface. The muons move at a speed of 0.8c straight down towards the Earth's surface. a. Calculate the time for the muons to travel from the balloon to the Earth's surface as determined by an observer on the Earth. b. Calculate the time for the muons to travel from the balloon to the Earth's surface as determined by an observer moving with the muons. Explain your reasoning. c. Stationary muons decay as shown in the figure above. Assume no muons pass the balloon at time t = 0 and determine the number that reach the Earth's surface. Give reasons for your answer.

4 1979B4. Determine the magnitude and direction of the force on a proton in each of the following situations. Describe qualitatively the path followed by the proton in each situation and sketch the path on each diagram. Neglect gravity. a. The proton is released from rest at the point P in an electric field E having intensity 10 4 newtons per coulomb and directed up in the plane of the page as shown below. b. In the same electric field as in part (a), the proton at point P has velocity v = 10 5 meters per second directed to the right as shown below. c. The proton is released from rest at point P in a magnetic field B having intensity 10 -l tesla and directed into the page as shown below. B P d. In the same magnetic field as in part (c), the proton at point P has velocity v = 10 5 meters per second directed to the right as shown below. B x x P x x x v x

5 1979B5. Four samples of ideal gas are each initially at a pressure P o and volume V o, and a temperature T o as shown on the diagram above. The samples are taken in separate experiment from this initial state to the final states I, II, III, and IV along the processes shown on the diagram. a. One of the processes is isothermal. Identify which one and explain. b. One of the processes is adiabatic. Identify this one and explain. c. in which process or processes does the gas do work? Explain. d. In which process or processes is heat removed from the gas? Explain. e. In which process or processes does the root-mean-square speed of the gas molecules increase? Explain. 1979B6. A light ray enters a block of plastic and travels along the path shown above. a. By considering the behavior of the ray at point P, determine the speed of light in the plastic. b. Determine what will happen to the light ray when it reaches point Q, using the diagram above to illustrate your conclusion. c. There is an air bubble In the plastic block that happens co be shaped like a plano-convex lens as shown below. Sketch what happens to parallel rays of light that strike this air bubble. Explain your reasoning.

6 1979B7. Two small spheres, each of mass m and positive charge q, hang from light threads of lengths l. Each thread makes an angle θ with the vertical as shown above. a. On the diagram below draw and label all forces on sphere I. b. Develop an expression for the charge q in terms of m, l, θ, g, and the Coulomb's law constant.

AP Physics B 1976 Free Response

AP Physics B 1976 Free Response The materials included in these files are intended for use by AP teachers for course and exam preparation in the classroom; permission for any other use must be sought from