The stars found in nebulae like the Orion Nebula probably formed
A) within the last few million years.
B) about 10 million years ago.
C) hundreds of millions of years ago.
D) billions of years ago.
E) at the beginning of the universe.
A
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Induction: Two uncharged metal spheres, #1 and #2, are mounted on insulating support rods. A third metal sphere, carrying a positive charge, is then placed near #2. Now a copper wire is momentarily connected between #1 and #2 and then removed. Finally, sphere #3 is removed. In this final state
A. spheres #1 and #2 are still uncharged. B. sphere #1 carries positive charge and #2 carries negative charge. C. sphere #1 carries negative charge and #2 carries positive charge. D. spheres #1 and #2 both carry positive charge. E. spheres #1 and #2 both carry negative charge.
If your mass is 60 kilograms on Earth, what is it on the Moon?
A. 120 kilograms, because the Moon's gravity is greater than Earth's B. 0 kilograms, because the Moon has no gravity C. 60 kilograms, because mass does not depend on gravity D. 360 kilograms, because the Moon is a spherical object
The vector sum of three co-planar forces
a. must be zero. b. must be perpendicular to one of the three. c. must be parallel to one of the three. d. must be perpendicular to the plane. e. may have any direction in the plane.
What is a rotation curve?
A) a graph showing how orbital velocity depends on distance from the center for a spiral galaxy B) a precise description of the shape of a star's orbit around the center of the Milky Way Galaxy C) a curve used to decide whether a star's orbit places it in the disk or the halo of a spiral galaxy D) a graph that shows a galaxy's mass on the vertical axis and size on the horizontal axis