The SI unit of force is the newton, symbol N. The base units relevant to force are: The metre, unit of length — symbol m The kilogram, unit of mass — symbol kg The second, unit of time — symbol s Force is defined as the rate of change of momentum. For an unchanging mass, this is equivalent to mass x acceleration. So, 1 N = 1 kg m s-2, or 1 kg m/s2. Historically, there have been a variety of units of force and conversion factors. Some of these are given in the table below. Exact conversions are shown in bold, others are quoted to seven significant figures. Unit Symbol Equivalent SI Value dyne dyn 10.0 µN grain-force grf 635.460 2 µN gram-force gf 9.806 65 mN poundal pdl 138.255 0 mN ounce-force (avdp) ozf 278.013 9 mN pound-force lbf 4.448 222 N kilogram-force kgf 9.806 65 N kilopond kp 9.806 65 N sthène sthène 1.0 kN kip (= 1 000 lbf) kip 4.448 222 kN US ton-force (= 2 000 lbf) (short) tonf (US) 8.896 443 kN tonne-force (= 1 000 kgf) (metric) tf 9.806 65 kN UK ton-force (= 2 240 lbf) (long) tonf (UK) 9.964 016 kN

The S.I. unit of force is

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The S.I. unit of force is Newton.

F = ma

1 Newton = 1 kg x 1 m/s²

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