Contrast finding the distances to seventh magnitude M3V and M3Ib stars
What will be an ideal response?
An M3V main sequence star that bright would be close, and you could use regular parallax shifts over six months to fix its distance. But a huge supergiant that faint must be so distant that only spectroscopic parallax can give us a clue to its distance.
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What do we mean when we say that the rotation curve for the Milky Way Galaxy is "flat"?
A) Gas clouds orbiting far from the galactic center have approximately the same orbital speed as gas clouds located further inward. B) The amount of light emitted by stars at different distances is about the same throughout the galaxy. C) The disk of a spiral galaxy is quite flat rather than spherical like the halo. D) All the galaxy's mass is concentrated in its flat, gaseous disk.
A thin-walled spherical tank with a diameter of 1.5 m and wall thickness of 65 mm has an internal pressure of 20 MPa. The maximum shear stress in the wall of the tank is approximately:
(A) 58 MPa
(B) 67 MPa
(C) 115 MPa
(D) 127 MPa
As a result of the ejection of planetesimals into the Oort Cloud, simulations indicate that Uranus and Neptune moved
A) closer to the Sun. B) further from the Sun. C) along their orbits at a different rate. D) from the inner solar system to the outer solar system. E) from the outer solar system to the inner solar system.
A plane convex lens is made of glass (n = 1.5) with one flat surface and the other having a radius of 20 cm. What is the focal length (in cm) of the lens?
A. 20 B. 30 C. 40 D. 10 E. 50