The English physicist Isaac Newton elaborated three important laws that have to do with the movement of bodies, an issue addressed by mechanics.
The laws, broadly speaking, can be explained as follows:
- First law. Also known under the name of Law of Inertia, states that bodies always remain in their state of rest or with their uniform rectilinear motion, unless another body exerts some kind of force on it.
- Second law. Also known as Fundamental principle of dynamics, states that the sum of all the forces exerted on a given body is proportional to its mass and acceleration.
- Third law. Also known as Principle of action and reaction, states that at the moment in which a certain body exerts some force on another, this other will always exert an identical force on that one, but in the opposite direction. It should also be taken into account that the opposing forces will always be located on the same line.
Examples of Newton’s Third Law (in everyday life)
- If we jump from a raft into the water, the raft moves backwards, while our body moves forward. This is an example of Newton’s third law since there is action (the jump) and reaction (the raft recoils).
- When we try to push someone while inside a pool. What will happen to us, even without the intention of the other, we will regress.
- When swimming in a pool, we look for a wall and push ourselves to gain momentum. In this case, an action and a reaction are also detected.
- When hammering a nail, it drives deeper and deeper into the wood as it is hammered, the hammer makes a backward movement, which is identified as the reaction of its own blow.
- When an individual pushes another who has a similar body, not only the pushed person will go backwards, but also the one who pushed him.
- When rowing a boat, while we move the water backwards with the oar, the water reacts by pushing the boat in the opposite direction.
- When two people pull in opposite directions on the same rope and it remains at the same point, it is also observed that there is an action and a reaction.
- When we walk, for example, on the beach, while with our feet we exert force forward with each step, we push the sand back.
- The operation of an airplane makes it move forward as a result of the turbines pushing to the opposite side, that is, backwards.
- A rocket moves thanks to the propulsion that burnt gunpowder gives it. Thus, while it goes backwards due to the action of a force, the rocket moves forward due to the action of the same force but in the opposite direction.