Meaning & use
energy density
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Meanings
noununcountablephysics
The amount of energy stored in a certain mass or volume of a fuel, food or battery.
Grammar: Usually uncountable: the energy density of gasoline.
Patterns
- the energy density of something
Lithium batteries have a high energy density, so phones can stay small.
The energy density of gasoline is far greater than that of wood.
Engineers are searching for fuels with greater energy density.
noununcountable
In nutrition, the number of calories a food contains for its weight.
Grammar: Often used in diet advice: foods of low energy density.
Patterns
- foods with high energy density
Nuts have a high energy density, so a small handful gives many calories.
Salad has a low energy density, so you can eat a lot of it.
Common combinations
- high energy density
- The battery's high energy density extends its range.
- low energy density
- Hydrogen gas has low energy density by volume.
- increase energy density
- Researchers hope to increase energy density in new batteries.
- energy density of fuel
- The energy density of fuel affects how far a rocket can travel.
Synonyms and how they differ
- calorific value
- Calorific value measures the heat released when a fuel burns, whereas energy density expresses energy per volume or mass in general.
- specific energy
- Specific energy is energy per mass only, while energy density often means per volume.
- power density
- Power density measures how quickly energy can be delivered, not how much is stored.
Word family
Commonly confused: energy density or power density?
energy density vs power density
Power density describes how fast energy can be released, while energy density describes how much is stored.
Practice
Phone makers prefer batteries with high ___ because they store more energy in a small, light package.
Choose one answer.
Energy density measures stored energy per weight or volume; the other terms describe failures or losses, not storage.
Make it your own
Write a sentence using “energy density”, then check it and compare it with the examples above.