Define 1kgf and **derive** the relation between kgf and S.I. Unit of Force.

One kilogram-force is the force due to gravity on a mass of 1 kg.

1 kgf = force due to gravity on a mass of 1 kg = mass 1 kg x acceleration due to gravity (g) m/s^{2}

Since the average value of g is 9.8 m/s^{2}

SI unit of force is Newton.

1 kgf = 9.8 N