Newton’s First Law of Motion

In the 17th century, Sir Isaac Newton published three laws pertaining to the motion of objects. The first law of Newton is an introduction of the object and the force acting on it. Mainly, Newton’s first law of motion deals with the motion of an object and its relation to force. Sir Isaac Newton’s laws were ascertained by several observations and experiments for over 200 years. 

The importance of Newton’s law is very crucial as they are related to everything we see or do in our daily lives. How things stay still, how they move, why we don’t float out of our bed, or why we fall on the floor of our house, all of these are related to Newton’s law. 

Sir Issac Newton’s First Law of Motion

The first law of motion says that a body will not begin to move unless and until an external force acts on it. 

It means that once a body is set in motion, the body will neither stop nor change its velocity until and unless some type of force acts upon it for once or more. Sometimes, the first law of motion is also understood as the law of inertia. 

Two conditions on which Newton’s first law of motion is dependent:

• When an object is at rest: 

The velocity (v=0) and acceleration (a=0) are at zero. And that’s why the object continues to be at rest. 

• When an object is in motion: 

In this, the acceleration(a=0) is equal to zero, but the velocity (v≠0) is not equal to zero. And that’s why the object continues, with constant motion and in the same direction. 

External Force

The change in the mechanical energy, which is either the potential energy in an object or the kinetic energy, is referred to as an external force. By the external agents, the external forces are caused. For example, air resistance, friction, and normal force. 

Let’s say we have taken a block on a smooth surface. And here, the smooth surface implies that there is no friction acting on the surface. The block is at rest. 

By examining the forces acting on the block, we understood that the force of gravity and the normal reaction by the surface are the only forces that are acting on the block. Therefore, the forces that are in the vertical direction are equally proportional to each other in magnitude. 

As there’s no other external force on the block, the forces cancel each other out. Newton’s first law of motion is confirmed as we see that the above block is at rest.  

Therefore, in inertial frames of reference, only Newton’s laws are valid. 

Sir Isaac Newton’s Second Law of Motion

Sir Isaac Newton’s Second Law of Motion says that the force is equal to the rate of change of momentum. Force equals mass times acceleration for a constant mass. 

The acceleration of an object depends upon two variables. Those are:

• The mass of the object 
• The force acting on the object

So, when the force acting upon an object is increased, the acceleration of the object is increased. Furthermore, when the mass of an object is increased, the acceleration of the object is decreased. 

Sir Isaac Newton’s Second Law’s equation

F = m a

Here F is force

M is the mass of the object

And a is acceleration

Sir Issac Newton’s Second Law application

To make an object move or stop, the amount of force required can be calculated with Newton’s second law of motion. Some examples are: 

• Kicking a ball. 

While kicking a ball in a particular direction, we exert force. The stronger we kick the ball, the further away it will travel. 

• Pushing a cart.

An empty cart in a supermarket is easier to push than a loaded one as more acceleration is required by more mass. 

Sir Issac Newton’s Third Law Of Motion

Newton’s third law states that when an object (A) exerts a force on (B), that same force must be applied on (A) in the reverse direction. 

Force can be classified into two categories: 

• First comes the contact force, such as frictional force. 
• Second comes the non-contact force, such as gravitational force. 

Sir Isaac Newton’s Third Law’s equation

FA = −FB

Conclusion:

Mainly Newton’s first law of motion deals with the motion of an object and its relation to force. 

Sometimes, the first law of motion is also understood as the law of inertia. The change in the mechanical energy, which is either the potential energy in an object or the kinetic energy, is referred to as an external force. To make an object move or stop, the amount of force needed can be calculated with Newton’s second law of motion. When two bodies interact with each other, they exert force on each other, and such types of forces are understood as pairs of actions and reactions by Sir Isaac Newton’s Third Law.