# Newton’s Laws of Motion and its Applications in Real Life

Sir Isaac Newton made many contributions to mathematics and physics. He developed the theory of gravitation in 1666 when he was only 23 years old. In 1686, he presented his three laws of motion in “Principia Mathematica Philosophiae Naturalis”.

Newton revolutionized science by developing his three laws of motion. Newton’s laws along with Kepler’s laws explained why planets move in elliptical orbits instead of circles.

## Let us discuss ‘Newton’s Laws of Motion and its applications in Real Life’ in detail:

**Newton’s First Law of Motion:**

Newton’s first law is known as the ‘Law of Inertia’. Inertia is the inherent power of a body. Because it tends to maintain its original state and oppose any change in its state. Mathematically, the inertia of a body is directly proportional to its mass; Therefore, heavier bodies require more energy or effort to change their state.

The first law of motion states that everything remains in its own state, or at a uniform speed in a straight line unless an external force prevents it from changing that state.

- An object remains in the state it is in. To make it move, an external force must be applied to it.
- An object in motion moves in a straight line. However, this statement may seem somewhat contrary to our daily life experiences. When we see a ball on the rough ground suddenly coming to rest. What happens is that the external force, which acts on the rolling ball, is in the opposite direction, i.e. friction, and therefore pushes it back.
- A force is required to change the original state along with the motion of the object.

### Applications of Newton’s First Law of Motion in Real Life:

- A coin is placed on top of a playing card if a glass is covered. And a sudden tap on the card causes the card to fly and the coin to fall into the glass. This happens because, due to inertia, the currency is still fixed.
- Dust is removed from a carpet by hanging the carpet and beating it with a stick. When the carpet is beaten, it moves back and forth. Dust particles, on carpets, remain at rest due to the inertia of rest and therefore fall.
- The passengers sitting on the bus suddenly got shocked when the bus started moving. This is caused by rest inertia, which acts on the passenger’s upper body; The bus falls behind them as it accelerates.
- A shot leaves a clean hole in a glass window pane; Where a glass window pane is broken into fine pieces by a stone. The stone, with its low speed, remains in contact with the glass window for a long time; While the particles in the glass window near the hole are unable to share the bullet’s high velocity and, therefore, remain unperturbed. Therefore, a hole is carved into the windowpane.
- An athlete usually runs for some distance before taking a long jump. He does so to overcome the inertia of rest and gain momentum; So there is a greater speed when jumping.
- When removing the ketchup from the bottom of the bottle, the bottle is turned upside down and punched at high speed. Thrusting helps the ketchup at the bottom acquire momentum inertia. Now, when the thrust suddenly stops, the ketchup, still in motion, comes out of the bottle.

**Newton’s Second Law of Motion:**

“If a force affects an object, the object gains acceleration, proportional to its strength and inversely proportional to its mass.”

Mathematically, Newton’s second law can be expressed through the following equation: **F=ma**. Here, F= Force, m= Mass, and a= Acceleration.

- The external forces are the ones that act on a body and exist outside or external of the system of that body.
- It is only the external forces that are responsible for producing any change in the state of the object.
- The force applied is directly proportional to the mass of the object and acceleration.

### Application of Newton’s second law of motion:

- You need a lot more energy to push a car than it takes to push a soccer ball.
- It is extremely difficult for one person to lift a box weighing 6 pounds, whereas the same box can be easily lifted by multiple people. The greater the number of people, the greater the amount of energy, and hence, the box can be lifted with less difficulty.
- A fielder’s arm is pulled back while catching a fast-moving cricket ball. A little delay slows the ball down. The second law states that the rate of change of motion is directly proportional to the force applied in that direction. In case, the ball is stopped quickly, the momentum suddenly decreases to zero. Because the rate of change of motion is fast, the player may injure his hand. When the player pulls his hand back, more time is given to change the speed rate to zero.
- Consider the game of tug-of-war, with two teams pulling on a rope in opposite directions. However, the movement of the rope will result in a net force on the rope. The net force, in turn, is determined by the difference in the forces exerted by the two parties. The team that pulls the hardest or exerts the most force wins.

**Facts:**

- Since the mass of a body, ‘m’, is always a scalar, force and acceleration are always positive.
- Newton’s second law is also called the ‘real law’ because the other two laws can be explained using the second law.
- The SI unit of force is newton (N). A force of 1N is defined as; A force of 1N acting on a body of mass 1kg and producing an acceleration of 1m/s2.

## Newton’s Third Law of Motion:

The third law is the Most used and most popular newton’s law of motion which is “For every action, there is an equal and opposite reaction.”

- Forces always exist in pairs. There can never be a single and isolated force.
- If two objects interact, the force, F12, exerted by object B on object A (called action) is equal in magnitude to the force, F21, exerted by object A on object B (called reaction).
- Although action-reaction is equal and opposite, they never cancel each other.

## Application of Newton’s third law of motion:

- It is the horizontal component of feedback, rendered by the ground, that enables us to walk, move forward, and run.
- As the fuel burns in the rocket, the gases released downwards create an upward reaction that is responsible for propelling the rocket upward.
- The action of a rotary lawn sprinkler is based on the third law of motion. The water coming out of the nozzle exerts an equal and opposite force on the back. This causes the sprinkler to rotate in the opposite direction and so the water spreads in all directions.
- When a man jumps from a boat to the shore, the boat goes backward.
- A fireman has to hold the pipe firmly so that it does not fall back; Water flowing from the pipe pushes it back.

## Validity of Newton’s laws of motion:

**Newton’s proposed laws of motion are only valid for:**

- The inertial frame or non-accelerated frame.
- Rigid body, which shows no deformation.
- non-relative bodies; Bodies moving with velocities less than the speed of light.
- Bodies larger than atomic size.

*Source of Information: StudiousGuy.Com, blog.praxilabs.com, byjus.com, britannica.com*