Magnetic reversals of the Earth's field have occurred on the average every 200,000 years over the past 5 million years. When was the last magnetic reversal?
a. about 200,000 years ago
c. about 990,000 years ago
b. 1792
d. about 780,000 years ago
D
Physics & Space Science
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The speed of sound in air at 0
is 331 m/s. What is the velocity of sound in air at a temperature of-30
?
A. 308 m/s B. 310 m/s C. 312 m/s D. 314 m/s E. 316 m/s
Physics & Space Science
A 0.200-H inductor is connected to a 60.0-Hz 120-V rms source. (a) What is the inductive reactance? (b) What is the rms current to the inductor? (c) If both the inductance and the frequency were doubled, what would be the rms current?
What will be an ideal response?
Physics & Space Science
The atomic theory was revived and put on a solid experimental foundation in about 1803 by
a. Proust. b. Dalton. c. Boyle. d. Lavoisier.
Physics & Space Science
The Mohs scale is based on how many minerals?
a. 8 b. 10 c. 12 d. 15
Physics & Space Science