Page Pressure Conversions psi .89 kPa Pressure may be expressed in standard units or in units of static fluid head in both SI and Imperial systems Common equivalencies are kPa .29 in mercury . mm mercury kPa .0 in water 0 mm water psi .0 in mercury 1. mm mercury psi 7. in water 0 mm water m H O .8 kPa Other pressure unit conversions bar 4. psi 0 kPa kg/cm 8. kPa 4. psi .98 bar atmosphere atm 01. kPa 4. psi Simple Harmonic Motion Velocity of P  ω R xm/s Acceleration of P ω x in m/s The period or time for a complete oscillation π ω seconds General formula for the period of S.H.M T π displacement acceleration Simple Pendulum T π L g T period or time in seconds for a double swing L length in metres