1
ENGR 130 MIDTERM 2 Questions and
Correct Answers
Question: 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?
Answer: 0.0055 kg/s
Reason:
m⋅ = ρVavgAc, Ac = πD^2/4
Question: 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.
Answer: 2.42 kg/s
Reason:
m∙in =m∙out =ρVavgA
Question: True or false: Flow work can be expressed in terms of other
properties.
Answer: True
Question: Which of the following energies are part of the total energy of
a flowing fluid?
Answer: Enthalpy
Kinetic energy
Potential energy
Question: Which of the following statements are true? (Select all that
apply.)
Pretest - Stuvia US
,2
Answer: -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
Question: 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?
Answer: 5 kg/s
Reason:
Mass flow rate is equal to the product of density and volumetric flow rate.
Question: True or false: In a single-stream, steady flow system, the
mass flow rates for the inlet and outlet must be the same.
Answer: True
Question: Which of the following statements are true? (Select all that
apply.)
Answer: -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.
Question: 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.
Answer: flow
Question: In a steady flow process, energy can be transferred by
______.
Answer: work, mass, and heat
Pretest - Stuvia US
, 3
Question: 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.
Answer: True
Question: During a steady-flow process, the fluid properties at an inlet
or exit must ______.
Answer: remain constant
Question: 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
Answer: hi
Question: In a single-stream, steady flow system, the mass flow rate
can be defined as the product of ___________, __________, and
___________.
Answer: Density, velocity, and area
Question: Turbine
Answer: produces shaft work
Question: Fan
Answer: Increases the pressure of a gas slightly and is mainly used to
move a gas
Pretest - Stuvia US
ENGR 130 MIDTERM 2 Questions and
Correct Answers
Question: 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?
Answer: 0.0055 kg/s
Reason:
m⋅ = ρVavgAc, Ac = πD^2/4
Question: 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.
Answer: 2.42 kg/s
Reason:
m∙in =m∙out =ρVavgA
Question: True or false: Flow work can be expressed in terms of other
properties.
Answer: True
Question: Which of the following energies are part of the total energy of
a flowing fluid?
Answer: Enthalpy
Kinetic energy
Potential energy
Question: Which of the following statements are true? (Select all that
apply.)
Pretest - Stuvia US
,2
Answer: -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
Question: 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?
Answer: 5 kg/s
Reason:
Mass flow rate is equal to the product of density and volumetric flow rate.
Question: True or false: In a single-stream, steady flow system, the
mass flow rates for the inlet and outlet must be the same.
Answer: True
Question: Which of the following statements are true? (Select all that
apply.)
Answer: -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.
Question: 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.
Answer: flow
Question: In a steady flow process, energy can be transferred by
______.
Answer: work, mass, and heat
Pretest - Stuvia US
, 3
Question: 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.
Answer: True
Question: During a steady-flow process, the fluid properties at an inlet
or exit must ______.
Answer: remain constant
Question: 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
Answer: hi
Question: In a single-stream, steady flow system, the mass flow rate
can be defined as the product of ___________, __________, and
___________.
Answer: Density, velocity, and area
Question: Turbine
Answer: produces shaft work
Question: Fan
Answer: Increases the pressure of a gas slightly and is mainly used to
move a gas
Pretest - Stuvia US
