**Mass **

Earth has a mass of 5.98 X 1024 kg. The average mass of the atoms that make up Earth is 40 u. How many atoms are there in Earth’s?

20 . Gold, which has a mass of 19.32 g for each cubic centimeter of volume, is the most ductile metal and can be pressed into a thin leaf or drawn out into a long fiber. (a) If 1.000 oz of gold, with a mass of 27.63 g, is. pressed into a leaf of 1.000 m thickness, what is the area of the leaf? (b) If, instead, the gold is drawn out into a cylindrical fiber of radius 2.500 m, what is the length of the

fiber?

21P. (a) Assuming that each cubic centimeter of water has a mass of exactly 1 g, find the mass of one cubic meter of water in kilograms. (b) Suppose that it takes 10.0 h to drain a container of 5700 m3 of water, What is the “mass flow rate,” in kilograms per second, of water from the container?

22P. What mass of water fell on the town in Problem 9 during the thunderstorm? One cubic meter of water has a mass of 103 kg.

23P. Iron has a mass of 7.87 g per cubic centimeter of volume, and the mass of an iron atom is 9.27 X 10-26 kg. If the atoms are spherical and tightly packed, (a) what is the volume of an iron atom and (b) what is the distance between the centers of adjacent atoms?

24P. Grains of fine California beach sand are approximately spheres with an average radius of 50 m and are made of silicon dioxide. A solid cube of silicon dioxide with a volume of 1.00 m3 has a mass of 2600 kg. What mass of sand grains would have a total surface area (the total area of all the individual spheres) equal to the surface area of a cube ‘I m on an edge?

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