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ENGR 130 MIDTERM 2 Questions and Correct
Answers/ Latest Update / Already Graded
Air is flowing in a pipe with 0.2 m in diameter at an average velocity of 0.1 m/s.
The density of air is 1.754 kg/m3. What is the mass flow rate?
Ans: 0.0055 kg/s
Reason:
m⋅ = ρVavgAc, Ac = πD^2/4
A nozzle is considered to be a steady flow device where a single stream flows in
and out. Steam with a density of 1.91 kg/m³ with an average velocity of 122 m/s
flows into a nozzle. Its inlet area of the nozzle is 104 × 10^−4 m^2. Determine its
mass flow rate at the nozzle outlet.
Ans: 2.42 kg/s
Reason:
m∙in =m∙out =ρVavgA
True or false: Flow work can be expressed in terms of other properties.
Ans: True
Which of the following energies are part of the total energy of a flowing fluid?
Ans: Enthalpy
Kinetic energy
Potential energy
Which of the following statements are true? (Select all that apply.)
Ans: -the steady-flow process is a process during which a fluid flows through a
control volume and does not change with time-during a steady flow process,
boundary work is zero-the steady flow implies that the fluid properties can change
from point to point, but at any point, they remain constant during the entire process
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The volumetric flow rate of water flowing through a pipe is 5 L/s, and the density
of water is 1 kg/L. What is the mass flow rate?
Ans: 5 kg/s
Reason:
Mass flow rate is equal to the product of density and volumetric flow rate.
True or false: In a single-stream, steady flow system, the mass flow rates for the
inlet and outlet must be the same.
Ans: True
Which of the following statements are true? (Select all that apply.)
Ans: -The rate of change of mass within a control volume minus the net flow rate in
and plus the net flow rate out of the control surface must equal to zero.
-In a steady flow process, the total rate of mass entering a control volume is equal
to the total rate of mass leaving it.
In an open system, when mass flows across control volume boundaries, some work is
required to push the mass into or out of the control volume, and this is known as
______ work.
Ans: flow
In a steady flow process, energy can be transferred by ______.
Ans: work, mass, and heat
True or false: The total energy for a flowing fluid consists of an additional term
when compared with the total energy for a nonflowing fluid.
True false question.
Ans: True
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During a steady-flow process, the fluid properties at an inlet or exit must ______.
Ans: remain constant
Nozzle
matches
Choice, A device that increases the velocity of a fluid at the expense of pressure
A device that increases the velocity of a fluid at the expense of pressure
Diffuser
matches
Choice, A device that increases the pressure of a fluid by slowing it down
A device that increases the pressure of a fluid by slowing it down
Ans: hi
In a single-stream, steady flow system, the mass flow rate can be defined as the
product of ___________, __________, and ___________.
Ans: Density, velocity, and area
Turbine
Ans: produces shaft work
Fan
Ans: Increases the pressure of a gas slightly and is mainly used to move a gas
Compressor
Ans: Increases pressure of gases and vapors
ENGR 130 MIDTERM 2 Questions and Correct
Answers/ Latest Update / Already Graded
Air is flowing in a pipe with 0.2 m in diameter at an average velocity of 0.1 m/s.
The density of air is 1.754 kg/m3. What is the mass flow rate?
Ans: 0.0055 kg/s
Reason:
m⋅ = ρVavgAc, Ac = πD^2/4
A nozzle is considered to be a steady flow device where a single stream flows in
and out. Steam with a density of 1.91 kg/m³ with an average velocity of 122 m/s
flows into a nozzle. Its inlet area of the nozzle is 104 × 10^−4 m^2. Determine its
mass flow rate at the nozzle outlet.
Ans: 2.42 kg/s
Reason:
m∙in =m∙out =ρVavgA
True or false: Flow work can be expressed in terms of other properties.
Ans: True
Which of the following energies are part of the total energy of a flowing fluid?
Ans: Enthalpy
Kinetic energy
Potential energy
Which of the following statements are true? (Select all that apply.)
Ans: -the steady-flow process is a process during which a fluid flows through a
control volume and does not change with time-during a steady flow process,
boundary work is zero-the steady flow implies that the fluid properties can change
from point to point, but at any point, they remain constant during the entire process
, 2 | Page
The volumetric flow rate of water flowing through a pipe is 5 L/s, and the density
of water is 1 kg/L. What is the mass flow rate?
Ans: 5 kg/s
Reason:
Mass flow rate is equal to the product of density and volumetric flow rate.
True or false: In a single-stream, steady flow system, the mass flow rates for the
inlet and outlet must be the same.
Ans: True
Which of the following statements are true? (Select all that apply.)
Ans: -The rate of change of mass within a control volume minus the net flow rate in
and plus the net flow rate out of the control surface must equal to zero.
-In a steady flow process, the total rate of mass entering a control volume is equal
to the total rate of mass leaving it.
In an open system, when mass flows across control volume boundaries, some work is
required to push the mass into or out of the control volume, and this is known as
______ work.
Ans: flow
In a steady flow process, energy can be transferred by ______.
Ans: work, mass, and heat
True or false: The total energy for a flowing fluid consists of an additional term
when compared with the total energy for a nonflowing fluid.
True false question.
Ans: True
, 3 | Page
During a steady-flow process, the fluid properties at an inlet or exit must ______.
Ans: remain constant
Nozzle
matches
Choice, A device that increases the velocity of a fluid at the expense of pressure
A device that increases the velocity of a fluid at the expense of pressure
Diffuser
matches
Choice, A device that increases the pressure of a fluid by slowing it down
A device that increases the pressure of a fluid by slowing it down
Ans: hi
In a single-stream, steady flow system, the mass flow rate can be defined as the
product of ___________, __________, and ___________.
Ans: Density, velocity, and area
Turbine
Ans: produces shaft work
Fan
Ans: Increases the pressure of a gas slightly and is mainly used to move a gas
Compressor
Ans: Increases pressure of gases and vapors
