Why were the mass and density of Pluto unknown until Charon was found?
What will be an ideal response?
Pluto is so distant that its disk was not resolved well, and it had no discernable gravitational influence on Uranus and Neptune (Lowell's prediction was just luck). But Charon's orbit let us find the mass of both objects, and the series of eclipses allowed us to calculate the sizes of both bodies with great accuracy.
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Named after the constellation they appear to radiate
A. Crater |
B. Stone meteorites |
C. Tektites |
D. Meteors |
E. Regmaglypts |
F. Meteor showers |
Compound Microscope: The distance between the object to be viewed and the eyepiece of a compound microscope is 18.0 cm. The focal length of its objective lens is 0.80 cm and the eyepiece has a focal length of 2.3 cm. The near-point distance of the person using the microscope is 25.0 cm. What is the magnitude of the total magnification of the microscope if it is designed for minimum eyestrain?
A. 120 B. 184 C. 200 D. 360 E. 480
Which of the following is evidence that solar activity affects Earth's climate?
A. The dust bowl of the 1930s in the United States coincided with the complete disappearance of sunspots during that time. B. The Maunder Minimum-a period of abnormally low sunspot numbers-coincided with abnormally cold northern winters. C. The Schwab Cycle-a period of abnormally numerous and large sunspots-preceded a 250-year drought in Africa. D. All of these choices are correct.
A metal blade spins at a constant rate of 5.0 revolutions per second about a pivot through one end of the blade. This rotation occurs in a region where the component of the earth's magnetic field perpendicular to the blade is 30 ?T. If the blade is 60 cm in length, what is the magnitude of the potential difference between its ends?
a. 0.24 mV b. 0.20 mV c. 0.17 mV d. 0.27 mV e. 0.34 mV