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
Question 2
If one could transport a simple pendulum of constant length from the Earth's surface to the Moon's, where the acceleration due to gravity is one-sixth (1/6) that on the Earth, by what factor would the pendulum frequency be changed?
a. about 6.0
c. about 0.41
b. about 2.5
d. about 0.17
Comparative sizes of the Earth and the Moon
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