91Ó°ÊÓ

Problem 12

At the surface of a freshwater lake the air pressure is 1.0 atm. At what depth under water in the lake is the water pressure 4.0 atm?

Problem 15

The density of platinum is \(21500 \mathrm{kg} / \mathrm{m}^{3} .\) Find the ratio of the volume of \(1.00 \mathrm{kg}\) of platinum to the volume of $1.00 \mathrm{kg}$ of aluminum.

Problem 16

In the Netherlands, a dike holds back the sea from a town below sea level. The dike springs a leak \(3.0 \mathrm{m}\) below the water surface. If the area of the hole in the dike is \(1.0 \mathrm{cm}^{2},\) what force must the Dutch boy exert to save the town?

Problem 18

The maximum pressure most organisms can survive is about 1000 times atmospheric pressure. Only small, simple organisms such as tadpoles and bacteria can survive such high pressures. What then is the maximum depth at which these organisms can live under the sea (assuming that the density of seawater is \(1025 \mathrm{kg} / \mathrm{m}^{3}\) )?

Problem 19

At the surface of a freshwater lake the pressure is \(105 \mathrm{kPa} .\) (a) What is the pressure increase in going \(35.0 \mathrm{m}\) below the surface? (b) What is the approximate pressure decrease in going \(35 \mathrm{m}\) above the surface? Air at \(20^{\circ} \mathrm{C}\) has density of $1.20 \mathrm{kg} / \mathrm{m}^{3} .$

Problem 20

A woman's systolic blood pressure when resting is \(160 \mathrm{mm}\) Hg. What is this pressure in (a) \(\mathrm{Pa},\) (b) \(\mathrm{lb} / \mathrm{in}^{2}\) (c) atm, (d) torr?

Problem 21

The gauge pressure of the air in an automobile tire is 32 lb/in \(^{2}\). Convert this to (a) \(\mathrm{Pa},\) (b) torr, \((\mathrm{c})\) atm.

Problem 22

An IV is connected to a patient's vein. The blood pressure in the vein has a gauge pressure of \(12 \mathrm{mm}\) Hg. At least how far above the vein must the IV bag be hung in order for fluid to flow into the vein? Assume the fluid in the IV has the same density as blood.

Problem 23

When a mercury manometer is connected to a gas main, the mercury stands $40.0 \mathrm{cm}$ higher in the tube that is open to the air than in the tube connected to the gas main. A barometer at the same location reads $74.0 \mathrm{cm}\( Hg. Determine the absolute pressure of the gas in \)\mathrm{cm}$ Hg.

Problem 25

A manometer using oil (density \(0.90 \mathrm{g} / \mathrm{cm}^{3}\) ) as a fluid is connected to an air tank. Suddenly the pressure in the tank increases by \(0.74 \mathrm{cm}\) Hg. (a) By how much does the fluid level rise in the side of the manometer that is open to the atmosphere? (b) What would your answer be if the manometer used mercury instead?