# Force

A force is that which when acting on a body that is free to move accelerates the motion of the body. The SI unit of force is the newton. 1 newton is defined as the force required to accelerate a mass of 1 kilogram by 1 metre per second per second.

Conversions | ||||||

1 dyne | = | 1x10^{-5} N | 1 poundal (pdl) | = | 0.138255 N | |

1 pound-force (lbf) | = | 4.44822 N | 1 ton-force | 9964.02 N | ||

1 kilogram-force (kgf) | = | 9.80665 N | 1 kip | = | 1000 lbf | |

1 sthene (sn) | = | 1000 N |

*Force**Relative Strength**Range*Strong 1 short ~10 ^{-15}mElectroweak Electromagnetic 10 ^{-2}long 1/r ^{2}Weak 10 ^{-9}short ~10 ^{-15}mGravitational 10 ^{-39}long 1/r ^{2}

**Fundamental Forces**

Concorde (thrust dry) | 5.6x10^{5}N |

Concorde (thrust with afterburner) | 6.76x10^{5}N |

Boeing 747 (thrust with 4 Rolls-Royce RB211) | 1.059x10^{6}N |

Ariane 5 (thrust at launch) | 1.3x10^{7}N |

Saturn 5 (thrust at launch) | 3.402x10^{7}N |

**See also: **Centrifugal Force, Compression, Coriolis Force, External Force, Kilogram Force, Newton, Pound Force, SI Units, Sthene, Tension, Weak Force.

**Subjects: ** Physics

- Advanced Physics for You, , Nelson Thornes

**Further reading:**