*Join Online class to watch Video explanation.
Newton’s First Law of Motion
Newton’s first law of motion implies that things cannot start, stop, or change direction all by themselves, and it requires some force from the outside to cause such a change. This property of massive bodies to resist changes in their state of motion is called inertia. The first law of motion is also known as the law of inertia.
The crucial point here is that if there is no net force resulting from unbalanced forces acting on an object, the object will maintain a constant velocity. If that velocity is zero, then the object remains at rest. And if an additional external force is applied, the velocity will change because of the force.
Newton’s Second Law of Motion
Newton’s second law of motion describes what happens to the massive body when acted upon by an external force. The second law of motion states that the force acting on the body is equal to the product of its mass and acceleration.
Mathematically, we express the second law of motion as follows:
f∝dP/dt
⇒f∝mv−mu/t
⇒f∝m(v−u)/t
⇒f∝ma
⇒f=kma
Where f is force, P is linear momentum, m is mass of the object, u is initial velocity, v is final velocity and a is acceleration.
In the equation, k is the constant of proportionality, and it is equal to 1 when the values are taken in the SI unit. Hence, the final expression will be,
F=ma.
Newton’s Third Law of Motion
Newton’s third law of motion describes what happens to the body when it exerts a force on another body.
Newton’s 3rd law states that there is an equal and opposite reaction for every action.
When two bodies interact, they apply forces on each other that are equal in magnitude and opposite in direction. To understand Newton’s third law with the help of an example, let us consider a book resting on a table. The book applies a downward force equal to its weight on the table. According to the third law of motion, the table applies an equal and opposite force to the book. This force occurs because the book slightly deforms the table; as a result, the table pushes back on the book like a coiled spring. Newton’s third law of motion implies the conservation of momentum.