Units of measurement

The International System S.I. of units is used. The primary units are the following:


meter (m) for length, kilogram (kgr) for mass and second ( sec) for time.

Force and stress are derived quantities, measured in Newton (N) and Pascal (Pa), respectively.
1 N=1 kg·m/sec2
1 Pa=1 N/m²

In practice the following units are used:

Concentrated force kN
Distributed force kN/m, kN/m²
Moment kNm
Stress and strength MPa(=N/mm²), kPa
Density kg/m3, t/m3
Modulus of elasticity GPa
Acceleration m/sec2 (g=9.81m/sec2≈10 m/sec2)

In the past, the technical system of units was used, where the fundamental units of measurement were m for length, sec for time and kg* weight for force.

By the definition of weight kilogram derives that:

1kg *=9.81 kg·m/sec2=9.81 N≈10N →
1 Ν=0.1 kg* → 1 kN=0.1 t* → 1 t*≈10 kN →
1 t */m≈10 kN/m → 1 kg*/cm2≈0.1 MPa → 1 MPa=0.1 kg*/cm2