investigate how heat and work, though both are energy in transit and both are
equivalent to each other according to the MEH, are differentiated.
Work is commonly defined as
Work is energy in transit.
In association with MEH, there has been a mistaking attempt to treat heat and work,
Q and W, in Eq. (22), in a parallel fashion. For instance, Newburgh and Leff wrote
“It is no more appropriate to speak of heat in a body than work in a body. Both
statements are not sensible” [10].
Objection to the use of heat is also made for a second reason: For instance, a 2004
paper reports: “When it comes to language about heat, there is consensus that
physicists’ language can be misleading, but little agreement about why it is misleading
or how it can be corrected” wrote Brookes et al. [11]. They concluded their study
Although physicists are quite aware that heat should be thought of as a process rather than a
substance, our coding shows that their language does not reflect this understanding.…
Physicists talk about heat predominately as if it were a substance.
Romer [12] made similar point
Heat presents one of our most series linguistic problems. Not only is it a common word in
the outside world, but in addition its frequent misuse within physics reinforces ancient and
erroneous views of the physical world [the caloric theory]…surely the experiments of Joule
and the careful thinking of the thermodynamicians of the second half of the nineteenth
century should have put it [i.e., the caloric theory] to rest forever. Yet, we continue to hear
vestiges of caloric theory in common talk…
Let us examine the first objection: Both heat exchange and work exchange are
energy-in-transition processes. It is true that we never speak of the work in a body.
But, work and heat are fundamentally different kinds of processes. Whereas heat
exchange is a one-step process (see below), work exchange other than compression
work is a two-step process. Only the first step of which is the process of mechanical
energy in transition across the system boundary of a receiving body, which naturally results in a gain of mechanical energy in the receiving body. Then, the internal
frictional dissipation––dissipatively converting mechanical energy into heat
energy––of the second step takes place resulting in a gain of thermal internal energy
in the body, which of course is neither “work” nor “mechanical energy” anymore.
That is why we do not speak of the work (or mechanical energy, except in the short
duration immediately after the exchange across the boundary) in a body.
In contrast, heat exchange is a one-step heat energy in transition, which naturally
results in gain of heat energy, i.e., thermal internal energy, in a body. There is no
corresponding reason as in the case of the two-step “work ! mechanical energy in
the body ! heat energy in the body,” for avoiding the language of heat energy in a
body. The same heat energy in transition remains heat energy in the body with its
form largely intact. This is because heat energy is the final form of energy for all
energy transformation processes. The same term of heat can be used for both heat
exchange, Q, and heat energy, a special (thermal) form of internal energy, U.
5.6 The Definition of Heat
105
equivalent to each other according to the MEH, are differentiated.
Work is commonly defined as
Work is energy in transit.
In association with MEH, there has been a mistaking attempt to treat heat and work,
Q and W, in Eq. (22), in a parallel fashion. For instance, Newburgh and Leff wrote
“It is no more appropriate to speak of heat in a body than work in a body. Both
statements are not sensible” [10].
Objection to the use of heat is also made for a second reason: For instance, a 2004
paper reports: “When it comes to language about heat, there is consensus that
physicists’ language can be misleading, but little agreement about why it is misleading
or how it can be corrected” wrote Brookes et al. [11]. They concluded their study
Although physicists are quite aware that heat should be thought of as a process rather than a
substance, our coding shows that their language does not reflect this understanding.…
Physicists talk about heat predominately as if it were a substance.
Romer [12] made similar point
Heat presents one of our most series linguistic problems. Not only is it a common word in
the outside world, but in addition its frequent misuse within physics reinforces ancient and
erroneous views of the physical world [the caloric theory]…surely the experiments of Joule
and the careful thinking of the thermodynamicians of the second half of the nineteenth
century should have put it [i.e., the caloric theory] to rest forever. Yet, we continue to hear
vestiges of caloric theory in common talk…
Let us examine the first objection: Both heat exchange and work exchange are
energy-in-transition processes. It is true that we never speak of the work in a body.
But, work and heat are fundamentally different kinds of processes. Whereas heat
exchange is a one-step process (see below), work exchange other than compression
work is a two-step process. Only the first step of which is the process of mechanical
energy in transition across the system boundary of a receiving body, which naturally results in a gain of mechanical energy in the receiving body. Then, the internal
frictional dissipation––dissipatively converting mechanical energy into heat
energy––of the second step takes place resulting in a gain of thermal internal energy
in the body, which of course is neither “work” nor “mechanical energy” anymore.
That is why we do not speak of the work (or mechanical energy, except in the short
duration immediately after the exchange across the boundary) in a body.
In contrast, heat exchange is a one-step heat energy in transition, which naturally
results in gain of heat energy, i.e., thermal internal energy, in a body. There is no
corresponding reason as in the case of the two-step “work ! mechanical energy in
the body ! heat energy in the body,” for avoiding the language of heat energy in a
body. The same heat energy in transition remains heat energy in the body with its
form largely intact. This is because heat energy is the final form of energy for all
energy transformation processes. The same term of heat can be used for both heat
exchange, Q, and heat energy, a special (thermal) form of internal energy, U.
5.6 The Definition of Heat
105