An up quark (u) has a charge +2/3, and a down quark (d) has a charge of -1/3. Which of the following describes a proton?
A) uuu
B) uud
C) udd
D) ddd
B
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Star A has an apparent magnitude = 3 and star B has an apparent magnitude = 5. Which star is brighter in our sky?
A) Star A B) Star B C) There is not enough information to answer the question. D) The two stars have the same brightness in our sky, but Star A is closer to us than Star B.
Does Venus’s surface experience meteorite impacts today? How do you know?
a. Yes. This is confirmed by Venus’s atmospheric composition, especially the abundance of deuterium. b. Not many. Since the atmosphere of Venus is very thick, most meteorites cannot reach the surface of Venus. c. No. Since Venus does not have a magnetic field, it does not attract meteoroids onto its surface. d. Yes. Meteorites fall onto Venus’s surface often because of the planet’s slow retrograde rotation and absence of moons.
A small airplane with a wing span of 12 m flies horizontally and due north at a speed of 60 m/s in a region where the magnetic field of the earth is 60 ?T directed 60° below the horizontal. What is the magnitude of the induced emf between the ends of the wing?
a. 50 mV b. 31 mV c. 37 mV d. 44 mV e. 22 mV
The sound of 40 decibels is
A) twice as intense as the sound of 20 decibels. B) four times as intense as the sound of 20 decibels. C) 10 times as intense as the sound of 20 decibels. D) 100 times as intense as the sound of 20 decibels. E) 1000 times as intense as the sound of 20 decibels.