How is a planet different than a star?
a. Planets are larger than stars.
b. Planets reflect light while stars produce their own light.
c. Stars move faster in the sky than planets.
d. Planets are brighter than stars.
B
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At last you are in a place where the heat and high density are no longer bothering you. However, although the density is very low, the gas around you is extremely high in temperature
In fact, the temperature is so high that it is emitting lots of X-rays, which are creating cancer-causing mutations in your body at a rapid rate. Well, at least the view is great! There are no stars anywhere within about 10,000 light-years of you, but at slightly greater distances your sky is brightened by many beautiful, star-filled structures, some with majestic spiral shapes. Where are you? A) You are in the universe when it was about 200 million years old, just before galaxies began forming. B) You are in the center of the Milky Way Galaxy, looking outward into the Local Group. C) You are somewhere between the Andromeda and Milky Way galaxies in the Local Group. D) You are in intergalactic space within a rich cluster of thousands of galaxies. E) You are in the outskirts of a galaxy whose nucleus is a powerful quasar.
Momentum and energy from focused laser beams can be used in nuclear fusion. This is because
A. light is not magnetic. B. the wavelength of light is small enough to penetrate each proton. C. light cannot be melted, so its pressure can confine the reaction. D. light can also function as a moderator, like graphite or water in a uranium reactor.
When a 20-V emf is placed across two resistors in series, a current of 2.0 A is present in each of the resistors. When the same emf is placed across the same two resistors in parallel, the current through the emf is 10 A. What is the magnitude of the greater of the two resistances?
a. 7.2 ? b. 7.6 ? c. 6.9 ? d. 8.0 ? e. 2.8 ?
The normal force that acts on a block of ice that slides on a ramp
A) is equal to mg at all angles. B) decreases as the slope of the ramp increases. C) becomes greatest when the ramp is vertical.