Newton's First Law

Newton’s laws of motion describe the relationship between an object and unbalanced forces acting on it. We know the effects of unbalanced forces. Sir Issac Newton laid down three laws of motion, therefore, it is sometimes known as Newton’s Laws of Motion. Let us explore the laws.

The law states that an object at rest or in uniform motion continues to be in that state unless acted upon by an unbalanced force.

Newton’s first law deals with the inertia. Inertia is the property of an object to maintain the same state. That is, if the object is at rest it will continue to remain at rest only, like a rock. If the object is at motion, then it will remain in motion only, like a ball rolling down a friction-less slope.

So, there are two types of inertias:

1.    The inertia of rest: The body tends to remain at rest.

2.    The inertia of motion: The body tends to remain in motion.

That is, Newton’s first law states that if the object is at rest then it will continue to be at rest unless an external unbalanced force is applied to it and if the object is in uniform motion then it will continue to remain in motion unless an external unbalanced force is applied to it.

Newton’s first law of motion discusses a body at inertia therefore, it is also referred to as the law of inertia.

Note: If the forces acting on an object at rest or in uniform motion is balanced then the body will continue to remain in the same state.

Newton’s first law of motion helps us understand experiences such as why we fall backward when a vehicle that we are in suddenly starts to move or why we fall forwards when a vehicle suddenly stops.

When the car that you are in suddenly starts to move, we fall backward because initially both car and you are in the state of rest (inertia of rest). As the vehicle starts to move forward, your body continues to be in the state of rest due to inertia of rest and you feel a backward push.

When the car suddenly stops, your upper body is still in motion while the car and your lower body come to rest and because of the inertia of motion, your upper body continues to move forward.