joule
/dʤu:l/
Học thuậtThân thiện
Definition
- Noun:
- A unit of energy in the International System of Units (SI): A joule is the standard unit of work or energy. It is defined as the amount of work done when a force of one newton displaces an object by one meter in the direction of the force.
- A unit of electrical energy: Specifically, one joule is equal to the work done when an electric current of one ampere passes through a resistance of one ohm for one second.
Examples of Usage
- Noun:
- Lifting a small apple one meter against Earth's gravity requires about one joule of energy.
- The battery stores approximately 10,000 joules of electrical energy.
- In physics, work is measured in joules.
Advanced Usage
- Scientific Context: The joule is used across physics, chemistry, and engineering to quantify energy, work, and heat.
- The heat capacity of water is about 4.18 joules per gram per degree Celsius.
- Derived Units: Many common units are defined in terms of joules.
- The kilowatt-hour, a unit for electricity billing, is equal to 3.6 million joules.
Variants and Related Words
- Kilojoule (kJ): A unit equal to one thousand joules.
- The nutritional information lists the energy content in kilojoules.
- Megajoule (MJ): A unit equal to one million joules.
- The rocket fuel provided several hundred megajoules of energy.
Synonyms
- Newton-meter (N·m): A synonymous unit for torque, though its use for energy is equivalent to the joule in the context of work.
- Watt-second (W·s): A direct equivalent, as one watt of power expended for one second equals one joule.
Related Phrases and Idioms
(Note: As a scientific unit, 'joule' is not typically used in idiomatic expressions or phrasal verbs. Its usage is primarily technical.)
Noun
- English physicist who established the mechanical theory of heat and discovered the first law of thermodynamics (1818-1889)
- a unit of electrical energy equal to the work done when a current of one ampere passes through a resistance of one ohm for one second