Page 21 - Aeronautical Engineer Data Book

Fundamental dimensions and units 11
10 m 2
1MPa or 1 MN

bar

bar atmosphere
1
1 bar 10 5 N/m 2 or 10 5 Pa 1.1097 kg/cm 2 1.013 bar 760 mm Hg 10.3 m H 2 O 14.7 psi
Rules of thumb: An apple ‘weighs’ about 1.5 newtons
A meganewton is equivalent to about 100 tonnes
An average car weighs about 15 kN
Fig. 2.1 Pressure relationships

KSI

21000

psi

2 0.0703 2 14.503
2 14.223 2 6.895.10 –3 2 0.06895

2 0.9807
Kg/cm 2 2 1.0197 Bar
2 145.03 2 0.1

2 10.0
2 10.197
2 0.09807
N/mm 2
(MPa)

Fig. 2.2 Pressure conversions