MCHE 469 Exam Questions with Correct Answers Graded A+
In deriving the fundamental law of conduction heat transfer, we used a special form of an infinite series
called a ___ ___ series. - Answers Truncated Taylor
The name of the fundamental equation of conduction heat transfer: - Answers Fourier's Law
Radiation heat transfer is more efficient in a vacuum than in a gas because it needs no: - Answers
medium
T/F: The net amount of radiation exchanged between a hot surface and a cold surface depends on the
surface radiative properties, the geometric configurations, and the fourth power of the absolute
temperatures. - Answers T
T/F: Convection heat transfer is governed by the Stefan-Boltzmann Law. - Answers F; Newton's Law of
Cooling
T/F: The thermal conductivity of a material determines how much heat can be transferred in a material,
whereas its thermal diffusivity indicates how fast heat can be transferred. - Answers T
T/F: If the outer radius of a pipe or tube is less than the critical radius, then the heat transfer will be
decreased, adding more insulation. - Answers F; R=k/h
T/F: Fin efficiency tells us how good a fin is with respect to the quantity of heat transfer for a given
design, whereas fin effectiveness indicates how fast heat can be transferred from a given fin. - Answers F
T/F: The 1D heat flow assumption is useful for fin problems when the fins are thin, and thus the problem
can be reduced to a 1D conduction-convection problem. Additionally, this assumption is justifiable
because empirical correlations for convection coefficients are only accurate to + or - 5%. - Answers F
T/F: In a convective cooling situation, we say that fins will be beneficial when the conductive resistance
is low & the convective resistance is high. - Answers T
T/F: The area for convection of a straight rectangular fin is equal to the product of its perimeter and the
cross sectional area. - Answers F
The name of the fundamental equation of radiation heat transfer is: - Answers Stefan-Boltzmann's Law
Name two ways that heat can be transferred in solids. Which is more effective? - Answers 1. Lattice
vibrations
2. Free electron transfer
-Free electron transfer is more effective
In deriving the fundamental law of conduction heat transfer, we used a special form of an infinite series
called a ___ ___ series. - Answers Truncated Taylor
The name of the fundamental equation of conduction heat transfer: - Answers Fourier's Law
Radiation heat transfer is more efficient in a vacuum than in a gas because it needs no: - Answers
medium
T/F: The net amount of radiation exchanged between a hot surface and a cold surface depends on the
surface radiative properties, the geometric configurations, and the fourth power of the absolute
temperatures. - Answers T
T/F: Convection heat transfer is governed by the Stefan-Boltzmann Law. - Answers F; Newton's Law of
Cooling
T/F: The thermal conductivity of a material determines how much heat can be transferred in a material,
whereas its thermal diffusivity indicates how fast heat can be transferred. - Answers T
T/F: If the outer radius of a pipe or tube is less than the critical radius, then the heat transfer will be
decreased, adding more insulation. - Answers F; R=k/h
T/F: Fin efficiency tells us how good a fin is with respect to the quantity of heat transfer for a given
design, whereas fin effectiveness indicates how fast heat can be transferred from a given fin. - Answers F
T/F: The 1D heat flow assumption is useful for fin problems when the fins are thin, and thus the problem
can be reduced to a 1D conduction-convection problem. Additionally, this assumption is justifiable
because empirical correlations for convection coefficients are only accurate to + or - 5%. - Answers F
T/F: In a convective cooling situation, we say that fins will be beneficial when the conductive resistance
is low & the convective resistance is high. - Answers T
T/F: The area for convection of a straight rectangular fin is equal to the product of its perimeter and the
cross sectional area. - Answers F
The name of the fundamental equation of radiation heat transfer is: - Answers Stefan-Boltzmann's Law
Name two ways that heat can be transferred in solids. Which is more effective? - Answers 1. Lattice
vibrations
2. Free electron transfer
-Free electron transfer is more effective
