If we could watch spiral arms from a telescope situated above the Milky Way over 500 million years, what would we see happen?
A) Stars will move through the spiral arms, bunching up closer as they pass through. Young hot stars will form and die within the arms before having a chance to move out.
B) The spiral arms will eventually unwind, as centripetal forces send the stars flying outwards into intergalactic space.
C) The spiral arms will eventually dissipate and fade away, since they are a temporary phenomenon that should only last for a million years or so.
D) The spiral arms will seem to "wind up," to wrap more and more tightly around the center of the Galaxy.
A
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The force due to gravity between two objects depends on I. the mass of each object. II. the distance each object is from Earth. III. the distance between the two objects. IV. the speed of light
a. I & II b. I & III c. II & IV d. I, II, & III e. I, II, III, & IV
Free Fall: An astronaut stands by the rim of a crater on the Moon, where the acceleration of gravity is 1.62 m/s2 and there is no air. To determine the depth of the crater, she drops a rock and measures the time it takes for it to hit the bottom. If the depth of the crater is 120 m, how long does it take for the rock to fall to the bottom of the crater?
A. 3.04 s B. 12.2 s C. 29.3 s D. 32.1 s E. 37.5 s
A uniform magnetic field is directed along the x axis. For what orientation of a flat, rectangular coil is the flux through the rectangle a maximum?
1.It is a maximum in the xy plane. 2.It is a maximum in the xz plane. 3.It is a maximum in the yz plane. 4.The flux has the same nonzero value for all these orientations. 5.The flux is zero in all cases.
Metallic bonding is due to
A) atoms bonding to hydrogen molecules. B) the transfer of electrons between atoms. C) unequal charge distributions around neutral molecules. D) the sharing of electrons by all atoms.