law of action and reaction
1
4.1
- noun
- Specialized
:
ley de acción y reacción
- When you jump off a small boat, the law of action and reaction causes the boat to move in the opposite direction.
Examples
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In everyday life, the law of action and reaction is observed when pushing against a wall; the wall pushes back with equal force.
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Does He, then, act under the law of action and reaction, as we do? Never....
Academic text (2010) -
According to physics, the law of action and reaction explains why a rocket propels itself forward as it expels gas backwards.
Synonyms
1
4.1
When one object pushes another, the other object pushes back equally
1
4.2
Every push on an object causes an equal push back in the opposite direction
1
3.9
Every force causes an equal force in the opposite direction
Surface Forms
Morphology
law + of + action + and + reaction
The phrase follows the compositional pattern 'law of X' so a learner who knows 'law', 'action' and 'reaction' can infer it refers to a general rule concerning actions and reactions; this is a direct, non-idiomatic combination. Although the precise physical detail (equal and opposite forces) is technical, the basic meaning — that there is a rule relating actions and reactions — is transparently derivable from the constituents and is cross-linguistically common.
Etymology
Law of action and reaction comes from Newton's idea: when you make an action, like a push, there is an equal reaction that 'pushes back'. So the name explains why, for example, a rocket goes up when its engines push down.