Which of the following devices makes use of an electromagnet?
a. relay
c. both A and B
b. motor
d. None of the above.
C
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Elementary Particles: Which of the following particles are leptons? (There may be more than one correct choice.)
A. protons B. neutrons C. electrons D. photons E. quarks
Which of the following is not one of the most common elements in living things?
a. oxygen b. carbon c. calcium d. iron e. nitrogen
Which phase of the Moon sets at noon?
A. waxing crescent B. full Moon C. third quarter D. new Moon E. None, the Moon always sets at sunrise.
You are driving along a highway at 25.0 m/s when you hear the siren of an emergency vehicle traveling at constant speed in the opposite direction on the other side of the highway
When the vehicle is approaching you, you hear the frequency of the siren as 2380 Hz, but when it is past you the frequency becomes 1680 Hz. What is the frequency of the siren? The speed of sound in air is 343 m/s. A) 1850 Hz B) 2000 Hz C) 2050 Hz D) 2010 Hz E) 1980 Hz