The graph is missing, however we can answer anyway.
In fact, this is the approximate percentage of the elements listed in the questions in the Earth's crust (data taken from wikipedia):
Iron 5.0 %
Calcium 3.6 %
Sodium 2.8 %
Potassium 2.6 %
Magnesium 1.5 %
of all of these, we see that the combination of two elements that makes up the closest number to 7% is calcium and sodium (3.6% + 2.8%=6.4%), therefore the correct answer is
Calcium and sodium.
Answer:
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Explanation:
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Answer:
The center of mass of the Earth-Moon system is 4.673 kilometers away from center of Earth.
Explanation:
Let suppose that planet and satellite can be treated as particles. The masses of Earth and Moon (, ) are and , respectively. The distance between centers is 384,403 kilometers. The location of the center of mass can be found by using weighted averages:
If and , then:
The center of mass of the Earth-Moon system is 4.673 kilometers away from center of Earth.
Answer:
Efficiency is the percent of work put into a machine by the user (input work) that becomes work done by the machine (output work).
Explanation:
It is a measure of how well a machine reduces friction.