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The joule, the SI unit of work and energy, is defined from newtons and meters. How large is one joule in everyday terms?
AEnough to lift a 100-gram apple about 1 meter
BEnough to lift a car several meters into the air
CRoughly the energy in a person's entire daily food intake
DToo small to ever be a meaningful unit in physics
Answer & Solution
Correct answer: A. Enough to lift a 100-gram apple about 1 meter
1. A joule is defined as one newton-meter, equal to one kilogram times meter squared per second squared.
2. In everyday terms, one joule is a small amount of energy, roughly enough to lift a 100-gram apple about 1 meter.
3. Lifting a car several meters, or supplying a whole day's food energy, would require many thousands of joules, far more than a single joule provides.
4. Despite being a small amount of energy per joule, the joule is still the standard SI unit used throughout mechanics, so it is far from meaningless.
_Source: OpenStax College Physics (CC BY 4.0), Ch 7 "Work, Energy, and Energy Resources", section 7.1 Work: The Scientific Definition_
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