Recent evidence suggests that Mars once had a global magnetic field. Assuming this is true, which of the following could explain why Mars today lacks a global magnetic field like that of Earth?
A) Mars rotates much slower than the Earth.
B) The Martian core is made of rock, while Earth's core is made of metal.
C) Mars's interior has cooled so much its molten core layer no longer undergoes convection.
D) Mars is too far from the Sun to have a global magnetic field.
C
You might also like to view...
If I0 = 10-12 W/m2 is the threshold of hearing, a sound with intensity I1 = 10-10 W/m2 will give a certain decibel level. Suppose a new sound has an intensity I2 = I12/I0 . What is the new decibel level?
a. 40 c. 10,000 b. 20 d. It will square the decibel level.
If you could watch a time-lapse movie of the interstellar medium over hundreds of millions of years, what would you see?
A) gas that is often moving at high speed, particularly after one or more supernovae, and constantly changing form between molecular clouds, atomic hydrogen, and hot, ionized bubbles and superbubbles B) gas that changes only in very slow and steady ways, so that the movie would in fact be quite boring C) The entire disk of the Milky Way would pulsate in and out as it contracts to form stars and then blows out in supernovae and then contracts to form stars again and so on. D) The movie would alternate back and forth between being very bright when there is a lot of gas and very dark when there is very little gas.
An empty spice bottle has an inner volume of 1.31 × 10^-4 m3 . It has a mass of 112 g when filled with air, and it displaces 1.63 × 10^-4 m3 of water when fully submerged. What fraction of the total volume of the bottle will be beneath the surface when it is placed in a tank of water?
a. 0.69 b. 0.81 c. 0.85 d. 1.00 e. 1.46
A positively charged electron is
A) called a positron. B) called a muon. C) called a proton. D) not found in nature. E) called a pion.