Question

State Newton’s laws of motion. Explain how the “newton” is defined from these laws.

Answer 1

Source: https://en.wikipedia.org/wiki/Newton%27s_laws_of_motion

First law

In an inertial frame of reference, an object either remains at rest or continues to move at a constant velocity, unless acted upon by a force.

Second law

In an inertial frame of reference, the vector sum forces F on an object is equal to the mass m of that object multiplied by the acceleration a of the object: $F = m\times a$ . (It is assumed here that the mass m is constant – see below)

Third law

When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.

Since "newton" is $\frac {kg\times m} {s ^ 2}$ , and according to Newton's second law, $F = m\times a$ therefore $[F] = kg\times\frac {m} {s ^ 2} = N$