Unit 8: Fluids

Question 1

What is the definition of density?

Answer 1

Density is the mass per unit volume of a substance, typically expressed in kg/m³.

Question 2

What is the formula for calculating density?

Answer 2

Density (ρ) = Mass (m) / Volume (V)

Question 3

True or False: The density of a substance changes with temperature.

Answer 3

True

Question 4

What is the principle of buoyancy?

Answer 4

An object submerged in a fluid experiences an upward force equal to the weight of the fluid displaced.

Question 5

What is Archimedes’ principle?

Answer 5

Archimedes’ principle states that the buoyant force on a submerged object is equal to the weight of the fluid it displaces.

Question 6

What is the equation for pressure in a fluid?

Answer 6

Pressure (P) = Force (F) / Area (A)

Question 7

What is the SI unit of pressure?

Answer 7

The SI unit of pressure is the Pascal (Pa).

Question 8

Fill in the blank: The pressure at a certain depth in a fluid is given by the equation P = ____ + ρgh.

Answer 8

P₀

Question 9

What does the variable ‘ρ’ represent in the equation P = P₀ + ρgh?

Answer 9

The variable ‘ρ’ represents the density of the fluid.

Question 10

What is Pascal’s principle?

Answer 10

Pascal’s principle states that a change in pressure applied to an enclosed fluid is transmitted undiminished to all parts of the fluid.

Question 11

What is the equation for hydrostatic pressure?

Answer 11

Hydrostatic pressure (P) = ρgh, where ρ is the fluid density, g is the acceleration due to gravity, and h is the height of the fluid column.

Question 12

True or False: Fluids can only flow in one direction.

Answer 12

False

Question 13

What is the continuity equation for incompressible fluids?

Answer 13

A₁V₁ = A₂V₂, where A is the cross-sectional area and V is the fluid velocity.

Question 14

What is Bernoulli’s equation?

Answer 14

Bernoulli’s equation states that P + 0.5ρv² + ρgh = constant, where P is pressure, ρ is density, v is velocity, and h is height.

Question 15

Fill in the blank: According to Bernoulli’s principle, as the speed of a fluid increases, the ____ decreases.

Answer 15

pressure

Question 16

What does the term ‘viscosity’ refer to?

Answer 16

Viscosity is a measure of a fluid’s resistance to flow.

Question 17

What is the unit of viscosity in the SI system?

Answer 17

The unit of viscosity is the Pascal-second (Pa·s).

Question 18

True or False: An ideal fluid has zero viscosity.

Answer 18

True

Question 19

What is the equation for the flow rate of a fluid?

Answer 19

Flow rate (Q) = A × v, where A is the cross-sectional area and v is the velocity of the fluid.

Question 20

What is laminar flow?

Answer 20

Laminar flow is a smooth, orderly flow of fluid in parallel layers, with no disruption between the layers.

Question 21

What is turbulent flow?

Answer 21

Turbulent flow is a chaotic flow regime characterized by eddies and vortices.

Question 22

Fill in the blank: The Reynolds number (Re) is used to predict whether flow is laminar or ____.

Answer 22

turbulent

Question 23

What is the critical Reynolds number for flow transition from laminar to turbulent in most cases?

Answer 23

The critical Reynolds number is approximately 2000.

Question 24

What is the equation for the Reynolds number?

Answer 24

Re = (ρvD) / μ, where ρ is fluid density, v is velocity, D is characteristic length, and μ is dynamic viscosity.

Question 25

What is the definition of surface tension?

Answer 25

Surface tension is the cohesive force at the surface of a liquid that causes it to behave as if it is covered by an elastic membrane.

Question 26

What is the unit of surface tension?

Answer 26

The unit of surface tension is Newton per meter (N/m).

Question 27

Fill in the blank: Capillary action occurs due to the combination of ____ and adhesive forces.

Answer 27

cohesive

Question 28

What is the formula for calculating the buoyant force?

Answer 28

Buoyant force (F_b) = ρ_fluid × V_displaced × g

Question 29

True or False: The weight of the fluid displaced is equal to the buoyant force.

Answer 29

True

Question 30

What is the relationship between pressure and depth in a fluid?

Answer 30

Pressure increases with depth in a fluid due to the weight of the fluid above.

Question 31

What is the significance of the hydrostatic paradox?

Answer 31

The hydrostatic paradox states that the pressure at a given depth is the same regardless of the shape or size of the container.

Question 32

What is the equation for calculating the force exerted by a fluid on a surface?

Answer 32

Force (F) = Pressure (P) × Area (A)

Question 33

What is the difference between absolute pressure and gauge pressure?

Answer 33

Absolute pressure is measured relative to a vacuum, while gauge pressure is measured relative to atmospheric pressure.

Question 34

Fill in the blank: The equation for the pressure at a depth h in a fluid is P = P₀ + ρgh, where P₀ is the ____ pressure.

Answer 34

atmospheric

Question 35

What is a fluid in physics?

Answer 35

A fluid is a substance that can flow and take the shape of its container, including liquids and gases.

Question 36

What is the formula for calculating the volume of a displaced fluid?

Answer 36

Volume displaced (V) = Area of base (A) × Height of fluid (h)

Question 37

True or False: An object will float if its density is greater than the density of the fluid.

Answer 37

False

Question 38

What is the term for the phenomenon when a fluid moves from an area of high pressure to an area of low pressure?

Answer 38

Flow

Question 39

What does the term 'hydraulic systems' refer to?

Answer 39

Hydraulic systems use incompressible fluids to transmit force and perform work.

Question 40

Fill in the blank: The principle of a hydraulic lift is based on ____'s principle.

Answer 40

Pascal

Question 41

What is the equation for the work done by a fluid in a hydraulic system?

Answer 41

Work = Pressure × Change in Volume

Question 42

What is the relationship between fluid velocity and cross-sectional area in a pipe?

Answer 42

As the cross-sectional area decreases, the fluid velocity increases (continuity equation).

Question 43

What is the term for the force per unit area exerted by a fluid?

Answer 43

Pressure

Question 44

What does Bernoulli's equation imply about the conservation of energy in flowing fluids?

Answer 44

Bernoulli's equation implies that the total mechanical energy of the flowing fluid remains constant.

Question 45

True or False: Viscosity affects the flow rate of a fluid.

Answer 45

True

Question 46

What is the effect of increasing temperature on the viscosity of a liquid?

Answer 46

Increasing temperature generally decreases the viscosity of a liquid.

Question 47

What is the formula for calculating the height of a fluid column in terms of pressure?

Answer 47

h = P / (ρg)

Question 48

What is the term for the upward force that a fluid exerts on an object submerged in it?

Answer 48

Buoyant force

Question 49

Fill in the blank: The speed of a fluid increases as it passes through a ____ area.

Answer 49

narrow

Question 50

What is the relationship between flow rate and velocity in a pipe?

Answer 50

Flow rate is directly proportional to the product of the cross-sectional area and velocity.

Question 51

What is the definition of incompressible fluid?

Answer 51

An incompressible fluid is one in which the density remains constant regardless of pressure changes.

Question 52

What is the significance of the hydrostatic pressure equation?

Answer 52

It describes how pressure in a fluid increases with depth due to the weight of the fluid above.

Question 53

What is the unit of measurement for fluid flow rate?

Answer 53

Cubic meters per second (m³/s)

Question 54

True or False: All fluids can be considered incompressible.

Answer 54

False