PhysicsLAB: 1994 Physics Olympiad Screening Test (Part 2)

AAPT Quiz
1994 Physics Olympiad Screening Test (Part 2)

16. A simple pendulum of length L and mass m is attached to a moving support.

In order for the pendulum string to make a constant angle θ with the vertical, the support must be moving to the:

A. right with constant acceleration a = g tanθ.
B. left with constant acceleration a = g tanθ.
C. right with constant acceleration a = g sinθ.
D. right with constant velocity

E. left with constant velocity

17. A Carnot cycle takes in 1000 J of heat at a high temperature of 400 K. How much heat is expelled at the cooler temperature of 300 K?

A. 0B. 250 JC. 500 JD. 750 JE. 1000 J

18. An ideal gas is expanded at constant pressure from initial volume V_i and temperature T_i to final volume V_f and temperature T_f. The gas has molar heat capacity C_P at constant pressure. The amount of work done by n moles of the gas during the process can be expressed:

19. The average translational kinetic energy of any ideal gas depends only on:

A. the absolute (Kelvin) temperature.
B. the mass of the gas.
C. the pressure of the gas.
D. the amount of the gas.
E. whether the gas is monatomic or diatomic.

20. A soap film of thickness t is surrounded by air. It is illuminated at near normal incidence by monochromatic light which has wavelength λ in the film.

A film thickness of ____ will produce maximum brightness of the reflected light.

A. ¼ λB. ½ λC. 1 λD. 2 λE. 4 λ

21. You are given two lenses, a converging lens with focal length +10 cm and a diverging lens with focal length –20 cm. Which of the following would produce a real image that is smaller than the object?

A. Placing the object 5 cm from the converging lens.
B. Placing the object 15 cm from the converging lens.
C. Placing the object 25 cm from the converging lens.
D. Placing the object 15 cm from the diverging lens.
E. Placing the object 25 cm from the diverging lens.

22. A source at rest emits waves with wavelength λ in a medium with velocity v. If the source moves to the right with velocity v_s, the distance between adjacent crests λ’ directly behind the source is:

23. Two sources, in phase and a distance d apart, each emit a wave of wavelength λ. See accompanying figure.

Which of the choices for the path difference ΔL = L₁ – L₂ will always produce constructive interference at point P?

Refer to the following information for the next two questions.

Two point charges of +4.00 µC and –9.00 µC are placed 1.00 m apart, as shown in the accompanying figure.

Assume the potential goes to zero as R goes to infinity.

24. The total electric field due to the two charges is zero at a point:

A. 3.00 m to the right of the –9.00 µC charge.
B. 0.40 m to the right of the +4.00 µC charge.
C. 0.31 m to the right of the +4.00 µC charge.
D. 0.80 m to the left of the +4.00 µC charge.
E. 2.00 m to the left of the +4.00 µC charge.

25. How much work is done moving the –9.00 µC charge from its original position to a new position 2.00 m from the +4.00 µC charge?

A. – 0.324 JB. –0.081 JC. +0.162 JD. +0.243 JE. +0.486 J

26. A point charge Q is placed at the center of a spherical conducting shell, the shaded part of the accompanying figure. A total charge of –q is placed on the shell.

The magnitude of the electric field at point P₁ a distance R₁ from the center is ____. The magnitude of the electric field at point P₂ a distance R₂ from the center is ____.

27. R₄, as shown in the figure, is a variable resistor.

In order for there to be no current through the ammeter, R₄ must be equal to:

A. R₂B. R₃C. R₁R₂/R₃D. R₁R₃/R₂E. R₂R₃/R₁

28. A resistor R dissipates power P when connected directly to a voltage source V, as shown in the accompanying figures.

What resistance R' must be connected in series with R to decrease the power dissipated in R to ½P?

29. The infinitely long straight wire carries a conventional current I as shown in the accompanying figure. The rectangular loop carries a conventional current I' in the counterclockwise direction.

The net force on the rectangular loop is:

30. A spatially uniform magnetic field of 0.080 T is directed into the plane of the page and perpendicular to it, as shown in the accompanying figure. A wire loop in the plane of the page has constant area 0.010 m². The magnitude of the magnetic field decreases at a constant rate of 3.0 x 10^–4 T/s.

What is the magnitude and direction of the induced emf?

A. 3.0 x 10^–6 V clockwise
B. 3.0 x 10^–6 V counterclockwise
C. 2.4 x 10^–5 V counterclockwise
D. 8.0 x 10^–4 V counterclockwise
E. 8.0 x 10^–4 V clockwise