2.10 Action and reaction Flashcards
What are action and reaction pairs?
A single force cannot exist by itself. Forces are always pushes or pulls between two objects. So they always occur in pairs.
What are the paired forces known as?
The paired forces are known as the action and the reaction, but it doesn’t matter which you call which. One cannot exist without the other.
If forces always occur in pairs, why don’t they cancel each other out?
The forces in each pair act on different objects, not the same object.
If a skydiver is pulled downwards, why isn’t the Earth pulled upwards?
It is! But the Earth is so massive that the upward force on it has far too small an effect for any movement to be detected.
Who was the first person to discover the action and reaction?
Isaac Newton was the first person to point out that every force has an equal but opposite partner acting on a different object. This idea is summed up by Newton’s third law of motion.
Newton’s third law of motion
To every action, there is an equal and opposite reaction.
What does newton’s third law explain?
If object A exerts a force on object B, then object B will exert an equal but opposite force on object A.
