How does Newton’s Third Law work?
Newton’s Third Law describes how physical and chemical phenomena go from a state of initial equilibrium to a state of final equilibrium . All the forces that act on a substance or an object tend to stabilize until the process ends. Once everything has been given, this final state can become the initial state for a new process.
Newton’s Third Law can be seen in all its splendor in the classic row of metallic spheres that, hanging at the same level, affect each other from end to end, leaving only the initial and the terminal oscillating . In this phenomenon, the sphere is taken from one end and suspended at a certain height, to be released.
When released, it marks a curved trajectory until it collides with the next sphere, communicating the impact throughout the entire row and reaching the last one, which rises up to follow the effect. In the end, it looks as if the two spheres on the sides were the only ones moving.
Another case in which Newton’s Third Law can be appreciated is the throwing of a ball against a wall. When we throw the ball, we transmit a force to it that makes it acquire a speed related to its mass. This force carries a direction towards the wall, a surface that remains immobile.
By not moving, the wall provides a resistance that will be a force in the opposite direction and with equal magnitude , which will act on the ball and make it bounce in a straight line or according to the angle with which it was thrown. The acceleration of gravity will also have an influence, accompanying the wall force and directing the ball to a state of rest.
20 examples of Newton’s Third Law
- The turbine of an airplane exerts a backward force with the air it releases, which causes a reaction in the opposite direction and with the same intensity that makes the airplane move forward.
- When an object is hung from a rope, the object exerts a downward force, but the rope exerts an upward force of equal intensity, which prevents the object from falling.
- The gunpowder that burns inside a rocket as it leaves propels the Earth downward, generating a force from the Earth on the rocket that causes it to fly.
- When a person jumps from a boat onto the dock he pushes the boat back and the boat propels the man forward.
- When striking a nail with a hammer, the nail exerts a counter force that causes the hammer to bounce back.
- When we fall from a certain height, the floor exerts a force to counteract that of our shoes when they touch the floor.
- For a bicycle in motion, the pedals exert a force opposite to that of the feet, which varies depending on how the transmission is positioned.
- The platform of a crane exerts an upward force to counteract the weight of the car it is loading.
- A trailer truck exerts a forward force, which overcomes the weight of the trailers and causes them to move behind it.
- When we dip a spoon into the cereal bowl, the utensil beats the contents to enter and load the serving. Our hand exerts the force to lift the cereal pieces and bring them to the mouth to eat them.
- In a gym, weights exert a force against the floor with their mass. The floor, in turn, corresponds to an identical force to support them.
- When pushing a broken car, one or more people exert a force contrary to its weight, to carry it from point A to point B.
- When more reagents are added to a chemical reaction, it tends to go further to create more products.
- When more products are added to a chemical reaction, it tends to make more reactants or to stop it, depending on the conditions.
- When pressure is applied to a chemical reaction, it tends to be directed toward the species with the fewest moles.
- When the pressure is reduced in a chemical reaction, it tends to be directed towards the species that have more moles.
- When the temperature of a chemical reaction is increased, it will advance to where the heat favors.
- If a person pushes another of similar weight, both move in opposite directions until they come to rest again, further away from each other.
- When we jump, we push the planet down and the earth pushes us up. This mutual effort and in equal intensity is appreciated differently because the planet is much larger.
- A person who is transported in a lake in a boat, goes rowing. With each paddle he pushes the water in a direction that allows him to get closer and closer to his destination.