The event horizon of a black hole is the point where _____
a. the mass of the black hole is concentrated in a singularity
b. the accretion disk around the black hole contacts its surface
c. the escape velocity equals the speed of light
d. tidal forces ionize infalling gas
e. an infalling particle reaches equilibrium with radiation pressure
c
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Three equal negative point charges are placed at three of the corners of a square of side d. What is the magnitude of the net electric field at the center of the square? (k = 1/4??0 = 8.99 × 109 N ? m2/C2)
What will be an ideal response?
Aluminum Rod#1 has a length L and a diameter d. Aluminum Rod#2 has a length 2L and a diameter 2d. If Rod#1 is under tension T and Rod#2 is under tension 2T, how do the changes in length of the two rods compare?
a. They are the same. b. Rod#1 has double the change in length that Rod#2 has. c. Rod#2 has double the change in length that Rod#1 has. d. Rod#1 has quadruple the change in length that Rod#2 has. e. Rod#2 has quadruple the change in length that Rod#1 has.
Internal energy is greater in a
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