How does counting craters help us estimate the age of a moon's surface?
What will be an ideal response?
Surface bombardment was much heavier early in the solar system's history. A surface with few craters implies many, or all, of the early craters were covered up by lava flows or other activity. The fewer the craters and the smoother the surface, the younger we assume it to be. The smoothest surfaces are the youngest.
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The main photo and the smaller inset (at the lower left) both show the same field of view containing a star-forming molecular cloud. One of the photos was taken in visible light and the other in infrared light. Which one is the infrared photo, and how do you know?
A) The main (larger) photo is the infrared because molecular clouds emit much more infrared light than visible light. B) The main (larger) photo is the infrared one because star-forming clouds generally are pink in color. C) The smaller inset photo is the infrared one because the cloud appears dark and infrared light is invisible. D) The smaller inset photo is the infrared because edge of the cloud glows red in the image.
Which subatomic particle or particles have no charge?
A) electrons and neutrons B) all subatomic particles have no charge C) neutrons only D) neutrons and protons
Two identical containers, A and B, hold equal amounts of the same ideal gas at the same Po, Vo and To. The pressure of A then decreases by a half while its volume doubles; the pressure of B doubles while its volume decreases by a half. Which statement correctly describes the temperatures of the gases after the changes?
a. TA = 0.5TB = To. b. TB = 0.5TA = To. c. TB = TA = To. d. TA = 2TB = To. e. TB = 2TA = To.
Two converging lenses, the first with focal length 40 cm and the second with focal length 331/3 cm, are separated by 10.0 cm. An object of height 6.0 cm is placed 20.0 cm in front of the first lens. What are the size and orientation of the final image?
A. 6.0 cm, upright B. 6.0 cm, inverted C. 24 cm, upright D. 24 cm, inverted E. 1.5 cm, inverted