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The distinction between heat and work only comes about in statistical physics. The idea is that while work is a transfer of energy through the macroscopic degrees of freedom which are described by macroscopic (i.e. thermodynamic) quantities (like pressure and volume), heat is a transfer of energy through the remaining degrees of freedom which are ignored in the macroscopic description.

In the above sense, the distinction between work and heat is in some way artificial. It is induced by our choice of which degrees of freedom we want to consider in our description of a physical system and which ones we choose to be ignorant about. This also means that temperature and entropy are basically dependent on the convention one chooses to describe the system. This perfectly matches the idea from information theory where the amount of information contained in a message is characterized by the so called Shannon entropy which is exactly the same thing as the physical entropy, except for the factor of $k_B$: a message like "The OP's name is 21Brunoh." contains exactly zero information to you because you already knew that. That same message may however be considered quite informative by someone unaware of this thread. Thus, information is an observer-dependent concept. Entropy characterizes the lack of information.

In thermodynamics however, there is a natural ("canonical") choice of the quantities of a physical system one can know about (like pressure, number of particles) and those which are inaccessible (like the positions and momenta of all the individual particles). The latter lead to a lack of information, characterized by the (physical) entropy. Changes in the observable/macroscopic quantities are called different forms of work, e.g. changes in pressure and volume are referred to as mechanical work. Changes in temperature and entropy are referred to as heat.

As an additional remark, please note that heat and work are meaningful only as changes of the internal energy. I'd always avoid writing $U=W+Q$ and instead use $\Delta U=\Delta W+\Delta Q$: changes in the internal energy are due either to work or heat. There is no such thing as the heat content or work content of some object, but one can talk about the energy content. You wouldn't talk about the amount of cash vs. the amount of credit card money you have in your bank account. Both paying in cash and by credit card are ways of changing the balance of your account, though.

The distinction between heat and work only comes about in statistical physics. The idea is that while work is a transfer of energy through the macroscopic degrees of freedom which are described by macroscopic (i.e. thermodynamic) quantities (like pressure and volume), heat is a transfer of energy through the remaining degrees of freedom which are ignored in the macroscopic description.

In the above sense, the distinction between work and heat is in some way artificial. It is induced by our choice of which degrees of freedom we want to consider in our description of a physical system and which ones we choose to be ignorant about. This also means that temperature and entropy are basically dependent on the convention one chooses to describe the system. This perfectly matches the idea from information theory where the amount of information contained in a message is characterized by the so called Shannon entropy which is exactly the same thing as the physical entropy, except for the factor of $k_B$: a message like "The OP's name is 21Brunoh." contains exactly zero information to you because you already knew that. That same message may however be considered quite informative by someone unaware of this thread. Thus, information is an observer-dependent concept. Entropy characterizes the lack of information.

In thermodynamics however, there is a natural ("canonical") choice of the quantities of a physical system one can know about (like pressure, number of particles) and those which are inaccessible (like the positions and momenta of all the individual particles). The latter lead to a lack of information, characterized by the (physical) entropy. Changes in the observable/macroscopic quantities are called different forms of work, e.g. changes in pressure and volume are referred to as mechanical work. Changes in temperature and entropy are referred to as heat.

As an additional remark, please note that heat and work are meaningful only as changes of the internal energy. I'd always avoid writing $U=W+Q$ and instead use $\Delta U=W+Q$: changes in the internal energy are due either to work or heat. There is no such thing as the heat content or work content of some object, but one can talk about the energy content. You wouldn't talk about the amount of cash vs. the amount of credit card money you have in your bank account. Both paying in cash and by credit card are ways of changing the balance of your account, though.

The distinction between heat and work only comes about in statistical physics. The idea is that while work is a transfer of energy through the macroscopic degrees of freedom which are described by macroscopic (i.e. thermodynamic) quantities (like pressure and volume), heat is a transfer of energy through the remaining degrees of freedom which are ignored in the macroscopic description.

In the above sense, the distinction between work and heat is in some way artificial. It is induced by our choice of which degrees of freedom we want to consider in our description of a physical system and which ones we chooses to be ignorant about. This is also means that temperature and entropy are basically dependent on the convention one chooses to describe the system. This perfectly matches the idea from information theory where the amount of information contained in a message is characterized by the so called Shannon entropy which is exactly the same thing as the physical entropy, except for the factor of $k_B$: a message like "The OP's name is 21Brunoh." contains exactly zero information to you because you already knew that. That same message may however be considered quite informative by someone unaware of this thread. Thus, information is a observer-dependent concept. Entropy characterizes the lack of information.

In thermodynamics however, there is a natural ("canonical") choice of the quantities of a physical system one can know about (like pressure, number of particles) and those which are inaccessible (like the positions and momenta of all the individual particles). The latter lead to a lack of information, characterized by the (physical) entropy. Changes in the observable/macroscopic quantities are called different forms of work, i.e. changes in pressure and volume are referred to as mechanical work. Changes in temperature and entropy are referred to as heat.

As an additional remark, please note that heat and work are meaningful only as changes of the internal energy. I'd always avoid writing $U=W+Q$ and instead use $\Delta U=\Delta W+\Delta Q$: changes in the internal energy are due either to work or heat. There is no such thing as the heat content or work content of some object, but one can talk about the energy content. You wouldn't talk about the amount of cash vs. the amount of credit card money you have in your bank account. Both paying in cash and by credit card are ways of changing the balance of your account, though.

The distinction between heat and work only comes about in statistical physics. The idea is that while work is a transfer of energy through the macroscopic degrees of freedom which are described by macroscopic (i.e. thermodynamic) quantities (like pressure and volume), heat is a transfer of energy through the remaining degrees of freedom which are ignored in the macroscopic description.

In the above sense, the distinction between work and heat is in some way artificial. It is induced by our choice of which degrees of freedom we want to consider in our description of a physical system and which ones we choose to be ignorant about. This also means that temperature and entropy are basically dependent on the convention one chooses to describe the system. This perfectly matches the idea from information theory where the amount of information contained in a message is characterized by the so called Shannon entropy which is exactly the same thing as the physical entropy, except for the factor of $k_B$: a message like "The OP's name is 21Brunoh." contains exactly zero information to you because you already knew that. That same message may however be considered quite informative by someone unaware of this thread. Thus, information is an observer-dependent concept. Entropy characterizes the lack of information.

In thermodynamics however, there is a natural ("canonical") choice of the quantities of a physical system one can know about (like pressure, number of particles) and those which are inaccessible (like the positions and momenta of all the individual particles). The latter lead to a lack of information, characterized by the (physical) entropy. Changes in the observable/macroscopic quantities are called different forms of work, e.g. changes in pressure and volume are referred to as mechanical work. Changes in temperature and entropy are referred to as heat.

As an additional remark, please note that heat and work are meaningful only as changes of the internal energy. I'd always avoid writing $U=W+Q$ and instead use $\Delta U=\Delta W+\Delta Q$: changes in the internal energy are due either to work or heat. There is no such thing as the heat content or work content of some object, but one can talk about the energy content. You wouldn't talk about the amount of cash vs. the amount of credit card money you have in your bank account. Both paying in cash and by credit card are ways of changing the balance of your account, though.

The distinction between heat and work only comes about in statistical physics. The idea is that while work is a transfer of energy through the macroscopic degrees of freedom which are described by macroscopic (i.e. thermodynamic) quantities (like pressure and volume), heat is a transfer of energy through the remaining degrees of freedom which are ignored in the macroscopic description.

In the above sense, the distinction between work and heat is in some way artificial. It is induced by our choice of which degrees of freedom we want to consider in our description of a physical system and which ones we chooses to be ignorant about. This is also means that temperature and entropy are basically dependent on the convention one chooses to describe the system. This perfectly matches the idea from information theory where the amount of information contained in a message is characterized by the so called Shannon entropy which is exactly the same thing as the physical entropy, except for the factor of $k_B$: a message like "The OP's name is 21Brunoh." contains exactly zero information to you because you already knew that. That same message may however be considered quite informative by someone unaware of this thread. Thus, information is a observer-dependent concept. Entropy characterizes the lack of information.

In thermodynamics however, there is a natural ("canonical") choice of the quantities of a physical system one can know about (like pressure, number of particles) and those which are inaccessible (like the positions and momenta of all the individual particles). The latter lead to a lack of information, characterized by the (physical) entropy. Changes in the observable/macroscopic quantities are called different forms of work, i.e. changes in pressure and volume are referred to as mechanical work. Changes in temperature and entropy are referred to as heat.

The distinction between heat and work only comes about in statistical physics. The idea is that while work is a transfer of energy through the macroscopic degrees of freedom which are described by macroscopic (i.e. thermodynamic) quantities (like pressure and volume), heat is a transfer of energy through the remaining degrees of freedom which are ignored in the macroscopic description.

In the above sense, the distinction between work and heat is in some way artificial. It is induced by our choice of which degrees of freedom we want to consider in our description of a physical system and which ones we chooses to be ignorant about. This is also means that temperature and entropy are basically dependent on the convention one chooses to describe the system. This perfectly matches the idea from information theory where the amount of information contained in a message is characterized by the so called Shannon entropy which is exactly the same thing as the physical entropy, except for the factor of $k_B$: a message like "The OP's name is 21Brunoh." contains exactly zero information to you because you already knew that. That same message may however be considered quite informative by someone unaware of this thread. Thus, information is a observer-dependent concept. Entropy characterizes the lack of information.

In thermodynamics however, there is a natural ("canonical") choice of the quantities of a physical system one can know about (like pressure, number of particles) and those which are inaccessible (like the positions and momenta of all the individual particles). The latter lead to a lack of information, characterized by the (physical) entropy. Changes in the observable/macroscopic quantities are called different forms of work, i.e. changes in pressure and volume are referred to as mechanical work. Changes in temperature and entropy are referred to as heat.

As an additional remark, please note that heat and work are meaningful only as changes of the internal energy. I'd always avoid writing $U=W+Q$ and instead use $\Delta U=\Delta W+\Delta Q$: changes in the internal energy are due either to work or heat. There is no such thing as the heat content or work content of some object, but one can talk about the energy content. You wouldn't talk about the amount of cash vs. the amount of credit card money you have in your bank account. Both paying in cash and by credit card are ways of changing the balance of your account, though.