Which best shields you from sunburn when at the beach?
A) a cloudy day
B) a sheet of glass between you and the Sun
C) frequent turning of your body
D) all of the above
E) none of the above
Answer: B
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Monkey Mo hangs from the middle of a horizontal rope. Tension in the rope is greatest if the rope
A) sags a lot. B) sags very little. C) sags or doesn't sag, for tension is the same in any case. D) none of the above
The origin of Earth's primitive ozone layer
A) is attributed to photosynthesis. B) traces back to the Cambrian period. C) is attributed to volcanic eruptions. D) helped to form the oceans.
A package of supplies is dropped from a plane, and one second later a second package is dropped. Neglecting air resistance, the distance between the falling packages will
A) depend on their weight. B) decrease. C) increase. D) be constant. E) be gt2.
When astronomers use Hubble's law to measure the distance to a galaxy they have to measure the ________ of the galaxy.
A. mass B. recessional speed C. rotational speed D. luminosity