A buzzer with frequency f0 is thrown straight upwards. On the buzzer's trip down, what is the frequency behavior heard by an observer below?
a. The frequency heard is still f0.
b. The frequency is a constant one greater than f0.
c. The frequency is an increasing one greater than f0.
d. The frequency is a decreasing one less than f0.
[Ques. 2] A straight wire of length l is oriented east-west and is in a magnetic field B pointing north. The wire is moving downward at a constant speed v. If the resistance of the rod is R, what is the current through the rod?
a. R/Blv
b. Blv/R
c. B2l2v2/R2
d. not given
[Ques. 3] Two cars, one in front of the other, are traveling down the highway at 55.0 m/s. The car behind sounds its horn, which has a frequency of 530 Hz. What is the frequency heard by the driver of the lead car? (vsound = 340 m/s)
a. 382 Hz
b. 735 Hz
c. 456 Hz
d. 530 Hz
e. 632 Hz
[Ques. 4] A straight wire of length l is oriented east-west and is in a magnetic field B pointing north. The wire is moving downward at a constant speed v. Which end of the rod is positively charged?
a. neither
b. the east end
c. the west end
d. both ends
[Ques. 5] An airplane flying with a constant speed flies from a warm air mass into a cold air mass. The Mach number will
a. increase.
b. decrease.
c. stay the same.
d. become unstable.
[Ques. 6] A metal rod is falling toward the surface of the Earth near the equator. As it falls, one end of the rod becomes positively charged due to the motional emf of the rod through the Earth's magnetic field. The rod is oriented so that
a. the rod is vertical with the positive end higher.
b. the rod is horizontal with the positive end toward the north.
c. the rod is horizontal with the positive end toward the east.
d. the rod is horizontal with the positive end toward the west.
[Ques. 7] A sound source of frequency 1 100 Hz moves at 40.0 m/s toward a listener who is at rest. What is the apparent frequency heard by the listener? (speed of sound = 340 m/s)
a. 1 230 Hz
b. 970 Hz
c. 980 Hz
d. 1 250 Hz
e. 870 Hz
[Ques. 8] An airplane with a wingspan of 79.0 m flies parallel to the Earth's surface at a point where the downward component of the Earth's magnetic field is 0.490 l04 T. If the induced potential between wingtips is 0.875 V, what is the plane's speed?
a. 54.3 m/s
b. 33.9 m/s
c. 226 m/s
d. 17 900 m/s
e. 111 m/s
[Ques. 9] A train station bell gives off a fundamental tone of 500 Hz as the train approaches the station at a speed of 30.0 m/s. If the speed of sound in air is 339 m/s, what will be the apparent frequency of the bell to an observer riding the train?
a. 456 Hz
b. 544 Hz
c. 250 Hz
d. 530 Hz
e. 339 Hz
[Ques. 10] The magnet moving past an object will produce eddy currents in the object if the object:
a. is magnetic material only.
b. is a conductor.
c. is an insulator.
d. is a liquid.
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