How do we know whether or not global warming is caused by humans?
A) From computer calculations that "predict" 20th-century temperatures based on natural variations, then on human-caused variations, and then on a mix of natural and human variations; the actual historical measurements then show that only natural variations are important.
B) From experiments in which excess carbon is injected into a laboratory-created Earth-like atmosphere, and the resulting temperature is measured.
C) From experiments in which a small experimental plot of forest is subjected to excess carbon, and the growth of the trees along with the temperature are then measured.
D) From computer calculations that "predict" 20th-century temperatures, based on natural variations, then on human-caused variations, and then on a mix of natural and human variations; the actual historical measurements then show the importance of human variations.
E) Actually, scientists have been unable to determine this.
A
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Thermal Expansion: The density of water at 0°C is 999.84 kg/m3 and at 4°C it is 999.96 kg/m3. A 1.0-L container, full to the brim with water at 4.0°C is placed in the refrigerator. By the time that the temperature of the water reaches 0.0°C, what volume of water has spilled from the container, assuming that the contraction of the container is negligible?
A. 1.1 × 10-7 m3 B. 1.2 × 10-7 m3 C. 1.3 × 10-7 m3 D. 1.4 × 10-7 m3 E. 1.5 × 10-7 m3
Refracting telescopes suffer from ____________________ aberration
Fill in the blank(s) with correct word
Can the lines in the figure below be equipotential lines?
a.
No, because there are sharp corners.
b.
No, because they are isolated lines.
c.
Yes, because any lines within a charge distribution are equipotential lines.
d.
Yes, they might be boundary lines of the two surfaces of a conductor.
e.
It is not possible to say without further information.
A satellite of mass M takes time T to orbit a planet. If the satellite had twice as much mass, the time for it to orbit the planet at the same altitude would be
A) 4T. B) 2T. C) T. D) T/2. E) T/4.