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Formulae and units
NAME FORMULA UNIT
ACCELERATION Change in speed/Time m/s2
BOYLE'S LAW P1V1 = P2V2 -
FORCE Mass x Acceleration N
CHARGE Current x Time C
COST of ELECTRICAL ENERGY Power (kW) x Time (hr) x Cost per unit £ or p
CURRENT Charge/Time A
DENSITY Mass/Volume kg/m3
ELECTRICAL ENERGY Voltage x Current x Time J
ELECTRICAL POWER Voltage x Current W
HEAT ENERGY Mass x s.h.c x Temperature change A
KINETIC ENERGY ½ mv2 J
MOMENT Force x Distance from the pivot Nm
LAW OF MOMENTS F1d1 = F2d2 -
MOMENTUM Change in speed/Time m/s2
POTENTIAL ENERGY Mass x gravity x Height mgh
POWER Work done/Time
Energy changed/Time
W
PRESSURE Force/Area Pa
RESISTANCE Voltage/Current Ω
SPEED Distance/Time m/s
TRANSFORMER No. of Primary turns/No. of Secondary turns
= Voltage on Primary/Voltage on Secondary
-
VOLTAGE Current x Resistance V
WORK Force x Distance J
WAVE SPEED Frequency x Wavelength m/s
 
 
 
© Keith Gibbs 2012