Star A is a main sequence star of spectral type F2 and star B is a white dwarf of spectral type B4. Which statement below is correct?
A) Star A appears brighter than star B.
B) Star B appears brighter than star A.
C) Star A is hotter than star B.
D) Star B is hotter than star A.
E) None of the above can be said about these two stars.
D
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In order to understand star clusters, we need to be able to estimate their ages. What technique do scientists use for this?
A) radioisotope dating B) counting the planets that have formed around the largest stars C) finding the main-sequence turnoff point of the stars D) calculating orbital parameters using Kepler's Laws E) measuring its parallax
The energy of the Sun starts as radiation, but is actually transported to its surface by convection, where it is radiated off into space at last
Indicate whether the statement is true or false
A physics professor pushes against a stationary wall, "working" up a sweat. Is he doing any actual physical work on the wall?
A) No--it's a law of nature that physics profs never do any actual work. B) No, because the force by his hands against the wall is balanced by the force by the wall pushing back. C) Yes, because he is exerting a force against the wall during a period of time. D) No, because the wall is not moving. E) Yes, because his arm muscles are moving other muscles through a distance.
As the speed of a moving fluid increases, the pressure in the fluid
A) increases. B) remains constant. C) decreases. D) may increase or decrease, depending on the viscosity.