Which of the following best describes the nature and origin of the atmospheres of the Moon and Mercury?
A) They have thin exospheres only, with gas coming from impacts of subatomic particles and photons.
B) They have thin tropospheres only, with gas coming from vaporization.
C) They have only small amounts of gas, all of which is left over from outgassing long ago.
D) They have thin atmospheres produced by outgassing, but still have the layers of a troposphere, thermosphere, and exosphere.
A) They have thin exospheres only, with gas coming from impacts of subatomic particles and photons.
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Two identical gliders slide toward each other on an air track. One glider moves at 1 m/s and the other glider moves at 2 m/s. They collide, stick, and move at
A) 1/2 m/s. B) 1/3 m/s. C) 1/6 m/s. D) 3/4 m/s. E) 1.5 m/s.
Three point charges are positioned on the x axis. If the charges and corresponding positions are +32 mC at x = 0, +20 mC at x = 40 cm, and -60 mC at x = 60 cm, what is the magnitude of the electrostatic force on the +32-mC charge?
a. 84 N b. 12 N c. 36 N d. 50 N e. 48 N
Why do we expect WIMPs to be distributed throughout galactic halos, rather than settled into the galaxy's disk?
A) WIMPs are lightweight enough that they have expanded out into the halo. B) WIMPs were produced by stars in the early stages of galaxy evolution and therefore are only found in globular clusters in the halo. C) WIMPS rarely interact with other particles and therefore cannot settle into galactic disks. D) Shock waves from generations of supernovae have blown the WIMPs out into the halo. E) WIMPs annihilate when they come into contact with ordinary matter, such as stars.
Once a current has been established in a superconducting material, how much energy is needed to keep it going?
a. None. b. Energy must be continuously provided as the same rate that was used to establish the current in the first place. c. Energy must continue to be provided at a lower rate than initially. d. Superconductors remove energy from the environment to maintain the current. e. The power needed to maintain the current is half that to establish it initially.