Question

explain the first law of motion with mathematical expression​

Answer 1

inertia of motion and inertia of rest

Answer 2

Newton's first law states that a body stays at rest if it is at rest and moves with a constant velocity unit if a net force is applied on it. Newton's second law states that the net force applied on the body is equal to the rate of change in its momentum.

F = ma

or F = m(v-u) / t

or Ft = mv - mu

That is, when F = 0, v = u for whatever time, t is taken. This means that the object will continue moving with uniform velocity, u throughout the time, t. If u is zero than v will also be zero, i.e., object will remain at rest.