different system and units used in MOS

1. CED, UET-P Muhammad Bilal
Mechanics of solids-Units
Two system of units are mostly used in problems
The basic units of stress in S.I units i.e. (International system) are N / m2 (or Pa)
MPa = 106
Pa
GPa = 109
Pa
KPa = 103
Pa
Sometimes N / mm2 Units are also used, because this is an equivalent to MPa. While
US customary unit is pound per square inch i.e. Psi
 In SI system the loads are mostly given in KN because newton is a small quantity while
the lengths are in mm, if we use the mm dimensions then the stresses will be in terms
of MPa otherwise if we go with meters the result will be in Pa
 For the US Customary system the loads are mostly in pounds(lb.) and the lengths are
in feet which needed to be converted into inches to get stresses in psi
 It is more appropriate and easy to work with SI therefore sometimes the loads are given
in KN but the distances in feet’s just to confuse the students and to check their control
on units in such problem convert the distances in feet’s to mm or m
 1ft=0.3041m=0.3041(1000)mm
System
international
US Customary