Question 1

Which of the following best defines the mass density $$\rho of a $$substance?

Accepted Answer

The mass per unit volume of a substance: $$\rho = \frac{m}{V}$$

Question 2

A 250 mL cup is filled with water and then with blood. The mass of blood is higher than that of water. What property explains this observation?

Accepted Answer

Blood has a higher density than water.

Question 3

Which of the following statements about the density of solids, liquids, and gases is correct?

Accepted Answer

Solids and liquids generally have higher densities than gases.

Question 4

Pressure is defined as:

Accepted Answer

The force acting perpendicularly per unit area: $$P = \frac{F}{A}$$

Question 5

A diver descends to a depth $$h in a $$lake. Which equation correctly relates the pressure at that depth to the surface pressure?

Accepted Answer

$$P = P_0$ + \rho g h$$

Question 6

Which of the following best describes the difference between gauge pressure and absolute pressure?

Accepted Answer

Absolute pressure is the sum of atmospheric pressure and gauge pressure.

Question 7

A mercury barometer is used to measure atmospheric pressure. If the height of the mercury column is $$h$$, which equation gives the atmospheric pressure?

Accepted Answer

$$P_{atm} = \rho_{Hg} g h$$

Question 8

Blood pressure is often measured in mm Hg. If a patient’s blood pressure is 130/80 mm Hg, what does this mean?

Accepted Answer

The maximum and minimum gauge pressures in the arteries are 130 mm Hg and 80 mm Hg, respectively.

Question 9

Pascal’s principle states that:

Accepted Answer

Pressure applied to an enclosed fluid is transmitted undiminished to every portion of the fluid and the walls of the container.

Question 10

A hydraulic lift uses Pascal’s principle. If a force $$F_1 is $$applied to a small piston of area $$A_1$$, and a larger piston of area $$A_2$$ lifts a car, which equation relates the forces and areas?

Accepted Answer

$$\frac{F_1$}{A_1$} = \frac{F_2$}{A_2$}$$

Question 11

Archimedes’ principle states that the buoyant force on an object immersed in a fluid is equal to:

Accepted Answer

The weight of the fluid displaced by the object.

Question 12

A block of wood floats in water with half its volume submerged. What can you conclude about the density of the wood?

Accepted Answer

The density of the wood is less than the density of water.

Question 13

A swimmer dives to a depth of 5 m in a freshwater lake ($$\rho = 1000\ \mathrm{kg/m^3$}). $$What is the gauge pressure at this depth? ($$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$49,000\ \mathrm{Pa}$$

Question 14

If the atmospheric pressure at sea level is $$1.01 	imes 10^5$\ \mathrm{Pa}$$, what is the absolute pressure 10 m below the surface of a freshwater lake? ($$ho = 1000\ \mathrm{kg/m^3$}$$, $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$1.99 	imes 10^5$\ \mathrm{Pa}$$

Question 15

A cube of side 0.1 m is completely submerged in water. What is the magnitude of the buoyant force acting on the cube? ($$\rho_{water} = 1000\ \mathrm{kg/m^3$}$$, $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$9.8\ \mathrm{N}$$

Question 16

Which of the following is a real-life application of Pascal’s principle?

Accepted Answer

A hydraulic car lift in an auto repair shop.

Question 17

If the density of oil is $$800\ \mathrm{kg/m^3$}$$, what is the pressure difference between two points 3 m apart vertically in the oil? ($$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$23,520\ \mathrm{Pa}$$

Question 18

A patient’s blood pressure is measured at the ankle, which is 0.5 m below the heart. If the density of blood is $$1060\ \mathrm{kg/m^3$}$$ and $$g = 9.8\ \mathrm{m/s^2$}$$, what is the additional pressure due to the height difference?

Accepted Answer

$$5,194\ \mathrm{Pa}$$

Fluid Mechanics: Density, Pressure, and Buoyancy

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