Newton’s laws

Newtonian Physics

Newton’s laws were invented by Newton and they form the basis of physics and they help in explaining most of the phenomena that are seen around us. Most of our everyday experiences can be explained exclusively by the Newton’s laws.

The Newton’s laws were among his findings which were a fundamental factor of the Enlightment age when Europe went from a state of almost unquestioning, church-endorsed belief in the infallibility and correctness of the Aristotelian worldview to a state where people, for the ?rst time in history, let nature speak for itself.

The Newton’s laws are mainly three: the Law of Inertia, Law of Dynamics and the Law of Reaction.  We shall look at each of the three laws briefly.

Law of inertia (Newton’s first law of motion)

The newton’s law of inertia states that “an object at rest or in uniform motion in a reference frame, remains so unless it is acted upon by an external force.”

This law shows that if an object remains at rest/stationary or in a constant uniform motion (without a change in its velocity) then the net external force acting on the object is zero. Net external force acting on an object is equal to the sum of all the forces acting on the object. If there is a net force acting on the body, the body will start moving if it was at rest or there will be a change in its velocity if it was in motion.

Let’s take for example, a box that is placed on the ground and it is at rest (not in motion). If a person exerts a force (pushes or pulls) on the box, the box will begin to slide on the ground.

But if two people exerts forces in opposite directions; one pushes and one pulls and the amount of forces exerted by each person is equal to the other, then the box will remain at rest (it will not move). But if one person exerts more force than the other, then the box will slid in the direction of the excess force.

On the other hand if an object is in motion and a force is exerted to it, the velocity of the object will either reduce or increase according to the direction of the net applied force. If the net force is in the same direction as the direction of the body’s velocity, then the velocity will increase. But if the net force is in the opposite direct to the velocity of the body, then the velocity of the body will reduce.

As mentioned during our Physics tuition classes, mathematically the law of inertia is stated as:
Law of Intertia

Where dv/dt is the derivative of the velocity which yields the change in velocity that is also called acceleration.