Unit 8 Practice Test

Question 1

Density is defined as _____________.

Answer 1

the mass per unit volume.

Question 2

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 2

0.695 kg

Question 3

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 3

Pressure and density decrease.

Question 4

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

Answer 4

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

Question 5

Consider an imaginary cube within a container of liquid. Which of the following statements concerning pressure and forces in a container of liquid in hydrostatic equilibrium is not correct?

Answer 5

Consider an imaginary cube within a container of liquid. Which of the following statements concerning pressure and forces in a container of liquid in hydrostatic equilibrium is not correct?

Question 6

Which of the following statements concerning pressure is not correct?

Answer 6

Although derived for a liquid, the formula P2 = P1 + pgh applies to fluids in general

Question 7

Consider the three flasks of water, each with the same area at the bottom and each having the same height. If flask A contains a larger volume of water than flask B, and flask B contains a larger volume of water than flask C, which of the following is correct?

Answer 7

The pressure at the base of all three flasks is the same.

Question 8

Consider a container that is 0.5 m x 0.5 m x 0.5 m filled with a liquid in hydrostatic equilibrium. Which of the following is incorrect?

Answer 8

The change in pressure between any two heights in a liquid is inversely proportional to the density of the liquid.

Question 9

Which of the following is not correct?

Answer 9

When a pressure is applied to a liquid in hydrostatic equilibrium, the pressure on the surface of the liquid is greater than at other points in the liquid.

Question 10

Which of the following is not correct?

Answer 10

If a force is applied to a fluid enclosed in a vessel, the pressure decreases as 1 / x, where x is the distance from the source of the force

Question 11

Consider a fluid of constant density in hydrostatic equilibrium. Which of the following is not correct?

Answer 11

Because the density p in Pascal’s principle is constant, Pascal’s principle only applies to liquids and not gases

Question 12

Consider a piston with small cross-sectional area A1 exerting a force F1 on the surface of a liquid, and a larger piston with cross-sectional area A2 exerting a force F2 on the surface of a liquid at its position. Which of the following is incorrect?

Answer 12

F2 = F1(A1/A2)

Question 13

Which of the following statements concerning buoyancy is not correct?

Answer 13

The net upward or downward force exerted on an object is called the buoyant force.

Question 14

The weight of an object is
W = m0g = P0V0g
Based on Archimedes’ principle, the weight of the volume of fluid the object displaces is: Fb = PfVfg (where Vf is the volume of fluid displaced). If the object is completely submerged in a liquid, Vo = Vf. Dividing the second equation by the first gives Fb/Wo = Pf/Po. Thus the buoyant force is Fb = Pf/Po*Wo. Which of the following is not correct?

Answer 14

The buoyant force on an object rising in the atmosphere is constant.

Question 15

Which of the following statements about Archimedes’ principle is incorrect?

Answer 15

Because pressure in a liquid is greater at a greater depth, the buoyant force depends on depth in the liquid.

Question 16

A series of solids are manufactured so that they increase in density by a constant amount. The solids are consecutively placed into a tub of water starting with the least dense and ending with the most dense. As the density of the solids increases, the buoyant force of water on a cubic foot of the submerged solid _____________.

Answer 16

remains the same

Question 17

Which of the following is not a characteristic of an ideal fluid?

Answer 17

An ideal fluid maintains a static-state flow.

Question 18

Applying the conservation of mass to ideal fluids, results in the equation of continuity. Which of the following statements about the derivation of the equation of continuity based on the diagram below is not correct?

Answer 18

The product of the density, the velocity, and the area A1 greater that the product of the density, the velocity, and the area A2.

Question 19

A cylindircal pipe carrying water slowly widens from a diameter (d1) of 20 cm to a diameter (d2) of 30 cm. If water flows into the pipe at 1 m/s, what is the speed of the water at the exit?

Answer 19

0.44 m / s

Question 20

Consider an ideal fluid. If the pressure increases, ____________.

Answer 20

without a change in height, the speed of the moving fluid decreases.

Question 21

Consider the apparatus shown in the diagram. Initially, the air is at rest. If the air is blown toward the left, the mercury will _____________.

Answer 21

rise in tube A.

Question 22

Water flows at a rate of 25 L/min through a horizontal pipe with a 7.0 cm diameter under a pressure of 6.0 Pa. At a point, calcium deposits reduce the cross-sectional area of the pipe to 30 cm62. What is the pressure at this point? Consider the water to be an ideal fluid and assume that 1 ml of water = 1 cm^3 water.

Answer 22

2.2 Pa

Question 23

Which of the following statements concerning surface tension is not correct?

Answer 23

Compared to most liquids, water has a high surface tension and its surface tension is not affected by differences in temperature.

Question 24

Stoke’s law can be used to determine ______________.

Answer 24

the radius of small spherical-shaped objects falling through a real fluid with laminar flow

Question 25

Which of the following statements is not correct?

Answer 25

Viscosity is the ratio of the strain rate to the shear stress.