Describe some of the early theories for why the Sun shines and why they are no longer accepted as viable
What will be an ideal response?
The Sun was once postulated to be a cooling ember, but that would have meant the Sun would have been much hotter in its immediate past (just a few hundred years ago) and people could not have lived in such a hot environment. Another idea was that the Sun shone through chemical burning (like a conventional fire on Earth), but this was dismissed because it could not generate and sustain sufficient brightness. A more modern hypothesis was that the Sun shone through the emission of thermal energy resulting from gravitational contraction, but this could only last for about 25 million years, far less than the age of Earth, before the Sun would have contracted to a point.
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Scattered light in the atmosphere is often partially polarized. The best way to determine whether or not light from a particular direction in the sky shows polarization is to
A. diffract the light through a single slit. B. squint while looking in that direction. C. rotate a piece of polaroid film about an axis parallel to the ray while looking through it in that sky direction. D. rotate a piece of polaroid film about an axis perpendicular to the ray while looking through it in that sky direction. E. reflect the rays from that direction on a shiny metal surface.
A high-diver of mass 70.0 kg jumps off a board 10.0 m above the water. If, two seconds after entering the water, his downward motion is stopped, what average upward force did the water exert on him?
The star named Sheat is of M2 II spectral type and luminosity class. Based on this information, which of the following are true? I. Sheat has a surface temperature less than the Sun. II. Sheat has a diameter that is greater than that of the Sun. III. Sheat is more luminous than the Sun. IV. Sheat is located near the upper left-hand corner in the H-R diagram
a. I & II b. II & IV c. II, III, & IV d. I, II, & III e. I, II, III, & IV
If the power factor for a series RLC circuit is 1.00, what is the phase constant?
A. 0.0
B. 30
C. 45
D. 60
E. 90