If any law has made it most to the general public’s references in conversations, it is the Newton’s third law of motion. It is the most popular scientific law that appeals to the masses. It is because of the third law of motion that a slap hurts to both the individuals involved, the one who beats and the one who’s beaten. No wonder those high fives with your friends hurt you too!
Newton’s third law of motion states that every action has an equal and opposite reaction. Action and reaction are in terms of force and are equal in magnitude and opposite in direction. The action-reaction pair are said to be inseparable, coexisting or not existing at all, for there has to be a reaction to every action. Imagine a universe without the third law, where you keep flapping your arms in the pool but could not swim? This law can be seen around us very frequently. Have a look!
Have a seat
How does it feel to sleep on a hard surface? The body feels the pain. It is because the surface exerts an equal and opposite force on you. Heavier the object, more is the opposite force applied. When you sit for too long on your chair, you start feeling pain. Now you know why this happens.
Walk you through it
You can’t walk on the slippery surface but you can easily do so on a rough surface. This is because the horizontal component of the force you exert on the floor for pushing it backwards gets a reaction force from the rough ground in terms of friction acting forwards on your feet, but slippery surface lacks this friction. Therefore, always take small steps on slippery grounds to minimize horizontal force you exert on it.
Hit it hard
Ever fired a gun? If you try one, please take care that it recoils. It means that the piston exerts a force on the bullet to propel it, but the reaction from the bullet causes the piston to move back, taking you along with it.
Ever felt a jerk while batting in cricket, or pain in leg while kicking a football? It is because when you exert the force on the ball to hit it hard, the ball also exerts equal force on you and this causes the jerk or pain you feel.
Slapping someone is not cool, more so, because this action also has equal and opposite reaction! Whatever force you exert on the cheek, the same force is exerted by the cheek on your palm. For that matter, hitting any surface will result in pain in your hand.
The birds use action and reaction pair while flying. The wings push the air downwards, and the air pushes the bird upwards. As stated above, the third law of motion helps us swim as we propel ourselves forward and push the water behind us.
To the stars!
Rocket propulsion is also a good example of Newton’s Third Law. The exhaust from the rocket pushes the ground and the ground pushes the rocket with equal and opposite force to cause the latter to move forward. If the third law of motion never existed, we would never have made it into the space!