# Thrust

## Description

Thrust is a reaction force described quantitatively by Newton’s second and third laws. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction on that system. The force applied on a surface in a direction perpendicular or normal to the surface is called thrust. Force, and thus thrust, is measured in the International System of Units (SI) as the newton (symbol: N), and represents the amount needed to accelerate 1 kilogram of mass at the rate of 1 metre per second squared.

In mechanical engineering, force orthogonal to the main load (such as in parallel helical gears) is referred to as thrust.

Related formulas## Variables

T | thrust generated (force) (N) |

v | speed of the exhaust gases measured relative to the rocket (m/s) |

dm | rate of change of mass with respect to time (mass flow rate of exhaust) (kg) |

dt | time (sec) |