AP Physics B 1980 Free Response Questions

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1 AP Physics B 1980 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 1980B1. A ball of weight 5 newtons is suspended by two strings as shown above. a. In the space below, draw and clearly label all the forces that act on the ball. b. Determine the magnitude of each of the forces indicated in part (a). Suppose that the ball swings as a pendulum perpendicular to the plane of the page, achieving a maximum speed of 0.6 meter per second during its motion. c. Determine the magnitude and direction of the net force on the ball as it swings through the lowest point in its path. D 1980B2. The electrical device whose symbol is shown above requires a terminal voltage of 12 volts and a current of 2 amperes for proper operation. a. Using only this device and one or more 3-ohm resistors design a circuit so that the device will operate properly when the circuit is connected across a battery of emf 24 volts and negligible internal resistance. Within the dashed-line box in the diagram below, draw the circuit using the symbol for the device and the appropriate symbol for each 3-ohm resistor. b. Using only this device and one or more 3-ohm resistors, design a circuit so that the device will operate properly when connected to a source that supplies a fixed current of 6 amperes. Within the dashed-line box in the diagram below, draw the circuit using the symbol for the device and the appropriate symbol. c. Calculate the power dissipation In each 3-ohm resistor used in the circuit in part (b).

3 1980B3. In a photoelectric experiment, radiation of several different frequencies was made to shine on a metal surface and the maximum kinetic energy of the ejected electrons was measured at each frequency. Selected results of the experiment are presented in the table below: a. On the axes below, plot the data from this photoelectric experiment. b. Determine the threshold frequency of the metal surface. c. Determine the work function of the metal surface. d. When light of frequency 2.0 x hertz strikes the metal surface, electrons of assorted speeds are ejected from the surface. What minimum retarding potential would be required to stop all of the electrons ejected from the surface by light of frequency 2.0 x hertz? e. Investigation reveals that some electrons ejected from the metal surface move in circular paths Suggest a reasonable explanation for this electron behavior.

4 1980B4. In the five pairs of graphs that follow, a curve is drawn in the first graph of each pair. For the other graph in each pair, sketch the curve showing the relationship between the quantities labeled on the axes. Your graph should be consistent with the first graph in the pair.

6 1980B5. An unstable nucleus, initially at rest, decays into two spherical fragments. Fragment A has radius r A charge q A, and rest mass m A ; fragment B has radius r B, charge q B, and rest mass m B. a. Suppose that after the decay process fragment A has velocity v A that is small-compared with the velocity of light. Develop an expression for the kinetic energy of fragment B in terms of v A, m A, and m B. At one stage in the decay process, the two fragments may be regarded as touching spheres, both at rest as shown above. Write expressions for each of the following. b. The electrostatic force between these two fragments at the instant they are touching c. The electrostatic potential U of these two fragments at the instant they are touching d. The rest mass m of the nucleus before it decays 1980B6. A helium atom of mass m moving with speed v zigzags back and forth between two parallel walls of length L separated by distance a as shown above. a. In terms of a, v, and θ calculate the time interval Δt between two successive collisions with the right-hand wall. b. In terms of m, v, and θ, calculate the magnitude of the momentum Δp imparted to the right-hand wall each time the atom collides with it. c. Calculate the average force that the atom exerts on the right-hand wall, and express the resulting pressure P on the wall in terms of θ, the volume V of the region bounded by the walls, and the kinetic energy E of the atom. d. Suppose, instead, that a photon of energy E is following the zigzag path. Calculate the magnitude of the momentum Δp it imparts to the right-hand wall in each collision, and express the resulting pressure P in terms of E, θ, and V.

AP Physics C 1976 Free Response Questions

AP Physics C 1976 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