Is space expanding within clusters of galaxies?
A) No, because the universe is not old enough yet for these objects to have begun their expansion.
B) No, because expansion of the universe affects only empty space, not space in which matter is present.
C) Yes, and that is why clusters tend to grow in size with time.
D) No, because their gravity is strong enough to hold them together even while the universe as a whole expands.
D
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The intensity of a sunspot is found to be 3 times smaller than the intensity emitted by the solar surface. What is the approximate temperature of this sunspot if the temperature of the solar surface is 5800 K?
a. 4400 K b. 470,000 K c. 1900 K d. 7600 K e. 1400 K
Action and reaction pairs of forces
A) always act simultaneously. B) may or may not act simultaneously. C) are independent of time.
A parallel plate capacitor of capacitance C0 has plates of area A with separation d between them. When it is connected to a battery of voltage V0, it has charge of magnitude Q0 on its plates. It is then disconnected from the battery and the space between the plates is filled with a material of dielectric constant 3. After the dielectric is added, the magnitudes of the capacitance and the potential difference between the plates are
A.
C0, 
V0.B.
V0.C.
D.
V0.E.