A centrifugal pump is used to lift water at a rate of 5.0 gallons per minute against a head of 50 feet of water. The efficiency of the pump is . What power input is required by the pump?
Calculate the depth to which Avogadro’s number of table tennis balls would cover Earth. Each ball has a diameter of 3.75 cm. Assume the space between balls increases their volume by and assume they are not crushed by their own weight. Use km as the value of the Earth’s radius.
What is the density of 18.0-karat gold that is a mixture of 18 parts gold, 5 parts silver, and 1 part copper? (These values are parts by mass, not volume.) Assume that this is a simple mixture having an average density equal to the weighted densities of its constituents.
Density of gold is 19.3 g/cm3.
Density of silver is 10.5 g/cm3.
Density of copper is 8.92 g/cm3.