Who conceived the idea of using a crystal for observing diffraction of x-rays?
a. Roentgen
b. von Laue
c. W. L. Bragg
d. W. H. Bragg
b
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Radioactive Decay: The half-life of cobalt-60 is 5.3 years, while that of strontium-90 is about 29 years. Suppose you have samples of both isotopes, and that they initially have the same activity (number of decays per second). What must be true of the numbers of cobalt-60 and strontium-90 nuclei in these samples?
A. There are more strontium-90 than cobalt-60 nuclei. B. There are equal numbers of cobalt-60 and strontium-90 nuclei. C. There are more cobalt-60 than strontium-90 nuclei. D. It is not possible to compare numbers of nuclei without knowing the masses of the samples.
Which is not a general classification of mountains?
a. Fault-block b. Fold c. Continental d. Volcanic
The graph below plots the escape velocity of several solar system objects along the vertical axis and the surface temperature along the horizontal axis. The lines plotted in the figure are the speeds of the fastest gas particles as a function of temperature for various gases. Which of the objects in this diagram has the greatest surface temperature?
a.
Ganymede
b.
Pluto
c.
Titan
d.
Triton
e.
Miranda
Notice that the parallax is greater (the apparent movement is larger) for the person than for the trees, and that the mountains do not appear to shift at all. Why?
A. The amount of parallax depends on an object's size, with greater parallax for larger objects. B. The amount of parallax depends on an object's size, with greater parallax for smaller objects. C. The amount of parallax depends on an object's distance, with greater parallax for more distant objects. D. The amount of parallax depends on an object's distance, with greater parallax for nearer objects.