Two long parallel wires are placed side-by-side on a horizontal table and carry current in the same direction. The current in one wire is 20 A, and the current in the other wire is 5 A
If the magnetic force on the 20-A wire has magnitude F, what is the magnitude of the magnetic force on the 5-A wire? No external magnetic fields are present. A) 4F
B) 2F
C) F
D) F/2
E) F/4
C
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You drive your car 5.0 km due East at 35 km/hr, and suddenly realize that you forgot your wallet. So, you return home, driving West at 40 km/hr, and upon arrival spend 10 minutes looking for it, and finally go back on the road for a total of 57.0 km due East. If your average velocity was 40 km/hr for the whole journey, what was your average speed on your last leg.
A. 49 km/hr B. 40 km/hr C. 45 km/hr D. 56 km/hr
A galaxy with a lot of dark matter would have a high mass-to-light ratio compared to the Sun
Indicate whether the statement is true or false
The "rare Earth hypothesis" holds that Earth-like planets will prove to be quite rare. Which of the following statements best sums up the current status of the debate over this hypothesis?
A) It is no longer discussed, because as part of its broad cover-up of UFOs, the United States government has classified all the material relating to this debate as Top Secret. B) We do not have enough data to settle the debate, because counterarguments can be made for each argument suggesting Earth-like planets may be rare. C) The debate raged for a while, but is now settled. We are now quite certain that Earth-like planets are rare. D) The debate raged for a while, but is now settled. We are now quite certain that Earth-like planets are common.
The elapsed time between two successive crossings of the same meridian by the Sun is known as ______________ day
a. one sidereal b. an apparent solar c. a 24-hour d. a mean solar