How do we determine the amount of dark matter in elliptical galaxies?
A) We measure the orbital velocities of star-forming gas clouds around the outer portions of the galaxy.
B) We measure the range of speeds of collections of stars at different distances from the galactic center and determine how much mass is interior to their orbits.
C) We count the number of stars in the galaxy and determine its volume, so that we can calculate the galaxy's density.
D) We search for dark lanes of dust and black holes within the galaxy.
E) We measure how fast the galaxy rotates as a whole.
B) We measure the range of speeds of collections of stars at different distances from the galactic center and determine how much mass is interior to their orbits.
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Force on a Moving Charge: We observe that a moving charged particle experiences no magnetic force. From this we can definitely conclude that
A. no magnetic field exists in that region of space. B. the particle must be moving parallel to the magnetic field. C. the particle is moving at right angles to the magnetic field. D. either no magnetic field exists or the particle is moving parallel to the field. E. either no magnetic field exists or the particle is moving perpendicular to the field.
What evidence suggests that life was common on Earth within a billion years of its formation?
A) Life must have formed early in order to produce the variety of lifeforms seen today. B) rocks older than 3.85 billion years with the carbon-12 to carbon-13 ratio typical of living organisms C) 3.5 billion year old rock structures formed by microbes called stromatolites D) A and C E) B and C
How would Jupiter be different if it rotated slowly?
What will be an ideal response?
A jogger runs halfway around a circular path with a radius of 60.0 m. What, respectively, are the magnitude of the displacement and the distance jogged?
a. 60.0 m, 188 m b. 120 m, 188 m c. 0 m, 377 m d. 120 m, 377 m e. 60.0 m, 377 m