The mass of Earth is 5.98 x 102 kg, and the mass of a single proton is 1.673 x 10-27 kg. Assuming Earth is made entirely of protons, use an order-of-magnitude calculation to estimate the number of protons that make up Earth. Then, calculate the
exact number of protons and express the answer in scientific notation with the correct number of significant digits.

Water is siphoned from a large tank and discharges into the atmosphere through a 50-mm diameter tube. the end of the tube is b = 2.1 m below the tank bottom which is a = 7.4 m deep, and viscous effects are negligible. determine the maximum height h over which the water can be siphoned without cavitation occurring. atmospheric pressure is 101.4 kpa, and the water vapor pressure is 1.79 kpa (absolute)