What is the one piece of evidence that suggests that the dinosaurs were made extinct by the impact of an asteroid 65 million years ago?
A) the crater from this impact can still be seen in the deserts of Arizona
B) a layer of sediment laid down at that time contains grains of shocked quartz, solidified rock droplets, and soot from global wildfires
C) a layer of sediment laid down at that time is littered with dinosaur fossils
D) dinosaur fossils are found in rock layers older than 65 million years but not younger than 65 million years
B
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A chamber that can be filled with different gases has placed in it a source of sound that in air produces a frequency of 200 Hz and a microphone to pick up the sound for frequency analysis. First the chamber is filled with helium (speed of sound 1 000 m/s at room conditions), then the helium is replaced with oxygen (speed of sound 330 m/s at room conditions), and then finally the helium is
replaced with carbon dioxide (speed of sound 269 m/s at room conditions). In which gas is the highest frequency of sound found by the microphone during this experiment? a. helium b. oxygen c. carbon dioxide d. They all have the same frequency of sound.
Harlow Shapley concluded that the Sun was not located at the center of the Milky Way Galaxy by
A) mapping the distribution of stars in the galaxy. B) mapping the distribution of gas clouds in the spiral arms. C) mapping the distribution of globular clusters in the galaxy. D) looking at the shape of the "milky band" across the sky. E) looking at other nearby spiral galaxies.
How fast would a rocket have to move past a ground observer if the latter were to observe a 9.4% length shrinkage in the rocket length? (c = 3.00 × 10^8 m/s)
a. 2.98 × 10^8 m/s b. 2.72 × 10^8 m/s c. 1.27 × 10^8 m/s d. 0.420 × 10^8 m/s e. 0.920 × 10^8 m/s
A megaparsec is equivalent to
a. 3.26 light-years. b. 206,265 AU. c. the age of our solar system. d. a million parsecs. e. the diameter of the Milky Way galaxy.