An apple. That's all it took for young Isaac Newton to figure out gravity! Sir Isaac Newton, also known as the father of physics, was indeed a gifted scientist. His rigorous study of nature fueled by curiosity of how things work gave us many theories that are accurate till this date.
Three Law's of motion are, perhaps, one of the widely acclaimed works of Sir Newton. The laws of motion are fairly simple but are often complicated due to the use of scientific terms. In this blog, we will simplify the three laws of motion and give examples of each one of them.
Newton's 1st law of motion
Law statement: An object either remains at rest or continues to move at a constant velocity, unless acted upon by an external force.
Explanation: It means that the velocity of a body will not change if there is no external force exerted on the body. This state of motion is also called inertia.
Example: Place a piece of cardboard on top of an empty cup. Now, place a coin on top of the cardboard. When you apply force on the cardboard by flicking it, it is set in motion. Since there is no direct force on the coin, it continues to be in rest. The coin is still in the state of inertia and it falls inside the cup.
Mathematical Representation of 1st Law
If ∑F = 0, then dv/dt=0
Where F=Force applied on object
v= velocity of the object
If summation of force exerted on an object is zero, then the change in its velocity i.e. acceleration is also zero.
Second Law of Motion
Law Statement: The change in momentum of an object is directly proportional to the sum of forces applied on it.
Explanation: Momentum is defined as mass of an object multiplied by its velocity. So if a force is applied on an object, it is directly proportional to the mass of the object and change in its velocity i.e. acceleration.
Example: It is easier to push a shopping cart that is empty rather than the one that is filled with items. Since the mass of an empty shopping cart is less, force required to accelerate it is also less.
Mathematical Representation of 2nd Law
F= dP/dt
F=d(mv)/dt
F=m dv/dt
F=ma
Where F= Force applied on the object
m= mass of the object
v= velocity of the object
a= acceleration
Third Law of Motion
Law Statement: When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.
Explanation: It can be summarized in simple words, “Every action has equal and opposite reaction”. It states that if the first object is applying a force on the second object, an equal and opposite force will be applied on the first object by the second object.
Example: When a rocket is launched, the rocket expels gases and exerts force on it by pushing it down. In turn, the gases apply equal and opposite force to propel the rocket upwards. This is a classic example of Newton’s Third Law of Motion.
Mathematical Representation of 3rd Law
If force exerted by object 1 on object 2 = F12
And force exerted by object 2 on object 1 = F21
Then, according to Newton’s third law of motion:
F12 = - F21
