What can we detect from matter that has crossed an event horizon?
A) Gamma-ray bursts
B) Radio waves if the matter was traveling fast enough
C) Visible light
D) X-rays if the matter was dense
E) Nothing
E
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Rotational Dynamics: A uniform, solid, 100-kg cylinder with a diameter of 1.0 m is mounted so it is free to rotate about fixed, horizontal, frictionless axis that passes through the centers of its circular ends. A 10-kg block is hung from a very light thin cord wrapped around the cylinder's circumference. When the block is released, the cord unwinds and the block accelerates downward, as shown in the figure. What is the acceleration of the block?
Fill in the blank(s) with the appropriate word(s).
Heating from _________ causes the top of Earth's stratosphere to be warmer than the bottom.
a. higher-energy particles in the solar wind b. convection c. the ozone layer absorbing UV light d. charged particles trapped by magnetic fields e. the greenhouse effect
What is the magnification of a magnifying glass of focal length 4.0 cm if the image is to be viewed by a relaxed eye with a near point of 25 cm?
A) 2.0 B) 3.0 C) 3.6 D) 4.0 E) 6.3
Earth's magnetism arises from
A) charged particles at rest on Earth's surface and on clouds in the lower atmosphere. B) the Wizard of Oz. C) electric currents in Earth's interior. D) electric currents in the sun. E) electric currents in the upper atmosphere.