Question

explain 2law of motion n derive an equation of force from it

Answer 1

The second law of motion states that the rate if change of momentum of an object is proportional to the applied unbalanced force in the direction of force.

let the mass of object be m
its initial velocity be u and final velocity be v in time t .
the initial and the final momentum will be , p1 = mu and p2= mv.
change in momentum = p1-p2
=mu-mv
=m (u-v)

the rate change of momentum = m×v-u / t

or, the applied force,
F is proportional to m × ( v-u ) /t
so,
F = km × ( v- u) / t
= kma
here a = v- u / t
k is a constant of proportionality.
the unit of force is chosen so that the value of k becomes 1 .
thus,

F = ma