8.1.1 Fluids, Density, and Pressure

Question 1

Fluids, Density, and Pressure

Answer 1

• Both fluids and solids consist of collections of atoms, so you can apply Newton’s laws to fluids as well as particles or rigid objects.
• Neither gases nor fluids have definite shapes. A gas expands very easily and can take any shape, while a fluid takes the shape of its container. Solids have definite shapes all the time.
• Two fundamental quantities for describing fluids are density (mass per unit volume) and pressure (force per unit area).
• A fluid at rest is said to be in hydrostatic equilibrium.

Question 2

Which of the following statements about fluids is not correct?

Answer 2

The density of an incompressible fluid depends upon the pressure to which the fluid is subjected.

Question 3

Which of the following statements concerning density is not correct?

Answer 3

Density is a property of the type of solid or fluid and is affected by the size of the sample.

Question 4

Which of the following is not a correct statement concerning liquids and gases?

Answer 4

The intermolecular forces for liquids and gases are, to a good approximation, almost the same.

Question 5

True or false?
Although neither gases nor liquids have a definite shape, liquids have a definite volume, while gases expand to fill any volume. Thus, liquids are fluids, and gases are not fluids.

Answer 5

false

Question 6

Density is defined as _____________.

Answer 6

the mass per unit volume.

Question 7

The mass of a liquid is 100 grams and it completely fills a container with dimensions 5.00 cm x 5.00 cm x 3.00 cm. What is the density of the liquid?

Answer 7

1.33 g / cm3

Question 8

Most of the Earth’s atmosphere is contained in a layer less than 6 kilometers (4 miles) thick. This layer is relatively thin. At any altitude in the atmosphere, the pressure of the surrounding air is referred to as atmospheric pressure. Which of the following statements concerning the atmosphere as altitude increases is correct?

Answer 8

Pressure and density decrease.

Question 9

Compressing a large thumbtack between your fingers illustrates one of Newton’s laws of motion. Which of the following correctly states that law?

Answer 9

If object A exerts a force on object B, then B exerts a force equal in magnitude and opposite direction on A.

Question 10

The density of gold is 19.3 times the density of water. The density of water is 1000 kg/m^3. What is the mass of a brick of gold that has dimensions 3.0 cm x 6.0 cm x 2.0 cm?

Answer 10

0.695 kg