In scientific writing, should I write energy is expended, cost or consumed?

Which term is preferable? As in the example,

Energy is expended/cost/consumed through deformation/vibration/friction.

  • Scientific and technical writing uses passive voice for method clarity and to avoid inappropriate anthropomorphism, but I don’t think it’s a general rule that passive voice has to be used throughout scientific works. – mRotten Jan 26 at 9:39
  • @OldPro "cost" in your sentence is a noun, not passive voice. – Acccumulation Jan 28 at 5:32
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    I think that it would be helpful if you were to edit your question. It certainly isn't clear to me what you are asking, in large part because the first sentence, at the end of which you have a question mark, is not a question but a statement, and the statment is not well formed. Do you mean something like, "In scientific writing when refering to energy, should I say that it is expended, or should I say that it is consumed?" ... but I am only guessing about exactly what you mean. – user02814 Jan 29 at 2:34

energy is said to be expended in English scientific texts as in these sentences:

1) Work Work is done when a force F is exerted to move an object over a distance d W = F × d unit of measure: the joule (J), 1 J = 1 N·m

Energy is expended when a force acts over some distance to move an object. Not all forces do work.

energy is expended

2) How much energy is expended in this reaction?

energy is expended, scientific publication

3) It can be seen that for all types of deformation and all metals investigated the percentage of the energy stored is high when the total energy expended during deformation is small, and that it decreases rapidly with increasing work done.

total energy expended

expended means "used up". The words cost and consumed are not used in your context in the form you have provided them. Consumed is used for electricity. Machines consume energy. And cost is about price, literal or not, so, it is irrelevant here.

[[You might want to take care not to expend too much energy in scientific writing. Caveat: joke on the question's wording. ]]

Please note: this answer contains examples. A comment did not provide enough room so I decided to post an answer.

That said, I am no materials scientist (unless you consider being a linguist being a scientist), but I can say this. All other things being equal, for a sentence in the form given by the OP

energy is A, B, or C [past participles of verbs expended, consumed or cost] through process 1, 2, 3 or 4.

It is my opinion that only the verb "expended" works there. Processes expend energy, they don't consume energy and they don't cost energy either.

USAGE, here, therefore is:

  • Energy is expended through a process or when a force is exerted.
  • A process expends (uses up) energy.

The last example posted by the OP is a comment: "for an elastic spring, the energy is expended partly on kinetic energy and partly on potential energy."

Energy is not expended there. Please note: Energy is stored in the elastic spring (compression) and it can be released when the spring elongates.

Proof of this from a professor at Stanford University

In physics, elastic energy refers to the energy released when a spring elongates. When a spring is compressed it stores energy that can be used later, at this point the spring contains elastic potential energy. 2 Releasing the spring, or elongating it, releases the elastic energy, allowing the spring to move.May 11, 2017

Elastic spring

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    I know nothing about physics particularly. But I would bet my soul that energy is said to be expended. And I thought I limited my answer to that and the deformation of metals*. That said, I am not seeing cost energy as you are saying it is used...I did say in my answer: in these sentences. Why don't you post an answer? – Lambie Jan 26 at 22:37
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    searching for "costs energy" [as noun] + friction=0; "cost energy" + deformation: returns verbs such as: "Stretching [a process] costs energy, which is stored as elastic energy." [from MIT]; Just as you said. But nothing like: energy costs [some thing]. The OP's question was in the form: energy is A, B, or C through process 1, 2, 3 or 4. So, I repeat, linguistically, one cannot say in a scientific paper: "energy is cost through process 1, 2, 3 or 4" [the verb cost is not used passively]; energy + consume through friction=1 hit; energy is expended through friction: 63 hits in good English. – Lambie Jan 27 at 17:08
  • And consumed through [a process] is prevalent but not in a materials' sense as given by the OP. – Lambie Jan 27 at 17:12
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    For someone with such high-level credentials, you certainly missed the point I was trying to make. My answer was really more to give examples from similar contexts, and to say that in the OP's context ("energy is expended/cost/consumed through deformation/vibration/friction") expended is best. Cost and consumed would not work there. You misread what I said, and then provide search terms outside the purview of the OP's actual question. I should have just made a comment and be done with it. And there is no need to shoo a fly with a hammer. – Lambie Jan 27 at 21:45
  • correx: been done with it. – Lambie Jan 27 at 22:19

The word to use depends a lot on the situation:

  • In cases where it is not easy to get the energy back into an easy-to-use form but the transformation caused by the energy is desired, it is common to say that energy is expended (or, less formally, spent or used) to achieve the desired result.
  • In cases where it is not easy to get the energy back and the transformation is not desired, it is common to say energy is lost.

The work expended for plastic deformation cannot be gained back completely. Some energy is lost in the process. (Slightly paraphrasing from Handbook of Physics).

Energy is expended to launch a rocket into orbit. However, more specifically, chemical potential energy is converted to kinetic energy and gravitational potential energy when a rocket is launched, although some energy is lost to friction between the rocket and the atmosphere.

A can crusher expends energy to crush a can, while a car running over a can loses energy due to plastic deformation of the can. A perpetual motion machine is impossible because all mechanical systems lose some energy to friction.

  • In cases where it is easy to get the energy back into its original form (or at least into a highly usable form), it is common to say the energy is stored or converted. Potential energy is stored in a spring, electrical energy is stored in a capacitor.
  • In chemistry, an endothermic reaction absorbs or requires energy. (In an exothermic reaction, energy is released or liberated.)
  • When concentrated or organized energy is dispersed or made disorganized, the energy is said to be dissipated. Damping a vibration dissipates energy. "Energy dissipation rate is the parameter to determine the amount of energy lost by the viscous forces in the turbulent flow."
  • Soundproofing materials absorb acoustic energy. Molecules absorb spectral (light) energy.
  • When something hot cools down and in the process heats something else up, energy is transferred from the hot thing to the cold thing.
  • The amount of energy it takes to do something is its energy cost or the amount of energy required.

    Foot contact time... is a strong predictor of locomotor energy costs, but it does not explain the variance in rate of energy expenditure during locomotion.... Nature, Scientific Reports Terrestrial locomotion energy costs vary considerably between species...

  • In cases where it is hard to get the energy into an easy to use form but you do it anyway, energy is harvested. In some sense, harvested is the passive form of expended, because the energy is being put to useful work, but the agency is given to some other system, not the system that is the source of the energy. The sun does not expend energy to create electricity on Earth, instead, solar arrays harvest the sun's energy to create electricity.
  • The amount of energy intentionally transferred out of a system (such as a laser or electrical generator) for some other purpose is its energy output or the amount of energy generated. An electrical generator generates energy that is used or expended by something else to do useful work.

There are lots of other examples, and it is best to look for specific examples as similar to your situation as possible. That said, you can generally fall back on energy being expended to do something you want or lost to something you would prefer did not happen.

With respect to energy, the word consumed is rarely used in scientific literature. I could only find it in biology, referring to living things that consume energy, meaning either the energy in the food they eat or the energy they expend on biological processes. Energy consumption is more commonly used in non-scientific literature to talk about the amount of energy used by devices (e.g. refrigerators, cars, lights) or groups of people using devices (e.g. United States per capita energy consumption) without respect to what the energy is used for.

Some more papers to look at: Swimmers spend/expend energy, A quantum refrigerator removes energy, and in the process energy is exchanged, transferred, and redistributed, reaching equilibrium when energy flows are balanced.


Friction dissipates energy.

1a : to break up and drive off
dissipate a crowd
1b : to cause to spread thin or scatter and gradually vanish
one's sympathy is eventually dissipated — Andrew Feinberg
1c physics : to lose (heat, electricity, etc.) irrecoverably

dissipate: Merriam Webster

The problem of vibrations in the blades of conventional engines is addressed by including an outer shroud disposed on the outer radius of each blade. Adjacent shrouds come in contact with each other to dissipate energy through friction at the interface, thereby alleviating vibrations. A drawback is that the edges of the shrouds at the point of contact wear out with time and can no longer reduce the vibrations, thus eliminating the mechanism for dissipation of energy.

Friction damper for gas turbine engine blades (patent)

  • i just edited the question. what if the system has no dissipative mechanism, as in elastic vibration or deformation where there's no energy loss but energy transfer, is 'dissipate' still the best choice here? – feynman Jan 24 at 7:20
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    No, you can use expended there if you like. Although expended tends to imply an effort over a decent period of time. You really need to provide sample sentence and context to get a drop-in word. – Phil Sweet Jan 24 at 11:35
  • let me give an example. for an elastic spring, the energy is expended partly on kinetic energy and partly on potential energy. is the 'expend' here appropriate? if not, what word will b a good sub – feynman Jan 24 at 13:46
  • Do you actually address the question? – Lambie Jan 26 at 19:18
  • @Lambie Well, it did before the Q edit. It was only about friction then. – Phil Sweet Jan 26 at 22:11

Energy can neither be destroyed nor created (conservation of energy) hence cannot be consumed per se - expended is your best choice here; Google NGram finds "cost" the least commonly-used construction of those you suggested in your post:

Google NGram

Albeit true that NGram Viewer is not restricted to scientific writings, there have been a number of well received peer reviewed papers demonstrating that in the more recent portions of the Google NGrams English corpus, scientific papers are in fact over-represented in proportion to the rest of the English corpus.

I will add one reference to support this useage:

Google books - Handbook of Physics

  • 'expend' is not commonly used in science. any other examples of using this word please? – feynman Jan 24 at 7:21
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    @feynman expend is commonly used when collocated with energy. My goodness.....I wonder where you got the idea it isn't used in science; it's very used in physics. – Lambie Jan 26 at 22:28

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