Most of the mass of a galaxy is contained in the
a. massive O and B stars in the galaxy.
b. H I regions of the galaxy.
c. H II regions of the galaxy.
d. dark matter of the galaxy.
e. disk of the galaxy.
D
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A nuclear reactor could explode like an atomic bomb
a. True b. False Indicate whether the statement is true or false
Which of the following materials has the highest dielectric constant?
a. air b. Mylar c. paper d. Pyrex glass e. water
Resistance and Resistivity: When a thin copper wire that is 178 m long is connected between a 1.2-V potential difference, a current of 2.0 amps flows through the wire. What is the diameter of this wire? The resistivity of copper is 1.72 × 10-8 ? ? m.
Fill in the blank(s) with the appropriate word(s).
Doppler Effect: You are driving along a highway at 25 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 speed of the vehicle? The speed of sound in air is 343 m/s.
A. 35 m/s B. 32 m/s C. 30 m/s D. 41 m/s E. 50 m/s