Q21 of 25 Page 130

State Newton's Second Law of motion. Derive a mathematical expression for Newton's second law.

Suppose an object of mass, m is moving along a straight line with an initial velocity, u. It is uniformly accelerated to final velocity, v in time, t with the impact of force, F throughout the time, t. The initial and final momentum of the object will be, p1 = mu and p2 = mv respectively.

The change in momentum p2 – p1


mv – mu


m(v–u)


The rate of change of momentum


Or, the applied force



= kma


k is a constant of proportionality, and its value is 1.


So, F = ma


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