Describe flux
What will be an ideal response?
Brightness is quite subjective, depending on both the physiology of eyes and the psychology of perception. To be scientifically accurate, you should refer to flux-a measure of the light energy from a star that hits one square meter in one second. With modern scientific instruments, astronomers can measure the flux of starlight with high precision and then use a simple mathematical relationship that relates light flux to apparent visual magnitude. Instead of saying that the star known by the charming name Chort (Theta Leonis) is about third magnitude, you can say its magnitude is 3.34. Thus, precise modern measurements of the brightness of stars are still connected to observations of apparent visual magnitude that go back to the time of Hipparchus.
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Fluid Flow: Ideal incompressible water flows through a horizontal pipe of cross-sectional area 10.0 cm2 at a pressure of 0.250 atm with a volume flow rate of 1.00 × 10-3 m3/s. At a valve, the effective cross-sectional area of the pipe is reduced to 5.00 cm2. What is the pressure at the valve?
A. 0.112 atm B. 0.157 atm C. 0.200 atm D. 0.235 atm
Which terrestrial world has the strongest magnetic field?
A) Mars B) Earth C) the Moon D) Venus E) Mercury
Two identical planets orbit a star in concentric circular orbits in the star's equatorial plane. Of the two, the planet that is farther from the star must have
A. the smaller period. B. the greater period. C. the smaller gravitational mass. D. the larger gravitational mass. E. the larger universal gravitational constant.
The cosmological principle is the ultimate extension of the Copernican principle to the entire universe, in that there is no center at all
Indicate whether the statement is true or false