Q: An ocean snorkeler dives to a depth of $$5.5\ \mathrm{m} in $$seawater ($$\rho = 1030\ \mathrm{kg/m^3$}). If $$atmospheric pressure is $$1.01 \times 10^5$\ \mathrm{Pa}$$, what is the absolute pressure at this depth?

$$1.6 \times 10^5$\ \mathrm{Pa}$$

Q: Water rises in a capillary tube to a height $$h. $$Which equation gives $$h in $$terms of surface tension $$\gamma$$, contact angle $$\theta_{contact}$$, density $$\rho$$, gravity $$g$$, and tube radius $$r$$?

$$h = \frac{2\gamma \cos \theta_{contact}}{\rho g r}$$

Q: Bernoulli’s equation for an ideal fluid states that along a streamline:

$$p + \frac{1}{2}\rho v^2$ = \text{constant}$$

Question 1

Which of the following best explains why gases are compressible but liquids are not?

Accepted Answer

Gases have molecules that are far apart, allowing them to be compressed, while liquids have molecules that are as close together as possible, making them incompressible.

Question 2

A 1 m × 1 m × 1 m cube is subdivided into 1 cm³ cubes. How many 1 cm³ cubes are there in the large cube?

Accepted Answer

$$10^6$$

Question 3

A piece of glass is broken into two pieces of different size. How do their densities compare?

Accepted Answer

The densities are equal: $$\$$rho_1$$ = \$$rho_2$$ = \$$rho_3$$

Question 4

Which equation correctly defines pressure in terms of force and area?

Accepted Answer

$$p = \frac{F}{A}$$

Question 5

A suction cup with a diameter of 10.0 cm is used to suspend an object from a ceiling. If the atmospheric pressure is $$101,000\ \mathrm{Pa}$$ and the area is $$A = \pi r^2$, what is the maximum mass that can be suspended? (Assume g = 9.8$$\ \mathrm{$$m/s^2$$}$$)

Accepted Answer

$$81\ \mathrm{kg}$$

Question 6

What is the hydrostatic pressure at a depth $$d in a $$liquid of density $$\rho$$ with surface pressure $$p_0$$?

Accepted Answer

$$p = p_0$ + \rho g d$$

Question 7

An ocean snorkeler dives to a depth of $$5.5\ \mathrm{m} in $$seawater ($$ho = 1030\ \mathrm{kg/m^3$}). If $$atmospheric pressure is $$1.01 	imes 10^5$\ \mathrm{Pa}$$, what is the absolute pressure at this depth?

Accepted Answer

$$1.6 	imes 10^5$\ \mathrm{Pa}$$

Question 8

Which of the following statements about hydrostatic pressure in a connected fluid is correct?

Accepted Answer

Hydrostatic pressure is the same at all points on a horizontal line through a connected fluid.

Question 9

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

Accepted Answer

$$p_{atm} = \rho g h$$

Question 10

According to Archimedes’ principle, what is the magnitude of the buoyant force $$F_B on an $$object submerged in a fluid?

Accepted Answer

$$F_B = \rho_f V_f g$$

Question 11

A heavy lead block and a light aluminum block of equal sizes are both submerged in water. Which experiences the greater buoyant force?

Accepted Answer

They both experience the same buoyant force.

Question 12

A block of wood floats in water with $$5.8\ \mathrm{cm}$$ submerged and in an unknown liquid with $$4.6\ \mathrm{cm}$$ submerged. If the density of water is $$1000\ \mathrm{kg/m^3$}$$, what is the density of the unknown liquid?

Accepted Answer

$$1300\ \mathrm{kg/m^3$}$$

Question 13

Which of the following best describes the condition for an object to float in a fluid?

Accepted Answer

The average density of the object is less than the density of the fluid.

Question 14

A barge filled with ore floats in a canal lock. If the ore is tossed overboard into the lock, what happens to the water level?

Accepted Answer

The water level falls.

Question 15

The pressure difference between the inside and outside of a soap bubble of radius $$R$$ and surface tension $$\gamma is$$:

Accepted Answer

$$\Delta p = \frac{4\gamma}{R}$$

Question 16

Water rises in a capillary tube to a height $$h. $$Which equation gives $$h in $$terms of surface tension $$\gamma$$, contact angle $$	heta_{contact}$$, density $$ho$$, gravity $$g$$, and tube radius $$r$$?

Accepted Answer

$$h = \frac{2\gamma \cos 	heta_{contact}}{ho g r}$$

Question 17

According to the equation of continuity, if water flows through a pipe that narrows, what happens to the speed of the water?

Accepted Answer

The speed increases in the narrower section.

Question 18

Bernoulli’s equation for an ideal fluid states that along a streamline:

Accepted Answer

$$p + \frac{1}{2}ho v^2$ = 	ext{constant}$$

Question 19

A constriction in a pipe causes the diameter to decrease from $$12\ \mathrm{mm} to$$ $$8\ \mathrm{mm}. If $$the flow speed in the wider section is $$4.0\ \mathrm{m/s}$$, what is the flow speed in the constricted section?

Accepted Answer

$$9.0\ \mathrm{m/s}$$

Properties of Fluids: Volume, Density, Pressure, and Buoyancy

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