The most common type of force is force due to gravity. All of us experience it in day to day life. When as a boy, Sir Isaac Newton wondered why an apple from the tree fell on the ground instead of being in the air or going up. He did not stop with that; however, he went to study the reasons and started researching. Ultimately, he introduced the concept of the gravitational force of earth Universal Law of Gravitation to the entire world.
According to Newton’s Second Law of Motion, also known as the Law of Force and Acceleration, a force upon an object causes it to accelerate.
F ∝ mv−mu/t
F ∝ ma (∵v−u/t =a)
F = k ma(k is a constant)
The force required to produce an acceleration of 1m/s2 on a body of mass 1kg is 1N
1 = k × 1 × 1
k = 1
∴ F = 1 × ma
F = ma
Thus, an object of constant mass accelerates in proportion to the force applied.