Thrust

Definition

Thrust refers to a force that a body experiences when it expels or accelerates mass in one direction. The thrust is experienced as per Newton's third law of motion in the direction opposite to the expulsion.

For instance, when an airplane or rocket expels fuel, the airplane or rocket is propelled in the direction opposite to the direction in which the fuel is expelled. The force propelling the airplane or rocket forward is called thrust.

If the material being expelled is being expelled at a velocity ${\overline {v}}$ and the mass explusion rate is ${\frac {dm}{dt}}$, the thrust experienced is

${\overline {v}}{\frac {dm}{dt}}$

Units and dimensions

Question	Answer
Scalar or vector?	Scalar
Instantaneous or time-cumulative?	Instantaneous
MLT dimensions	$MLT^{-2}$ MLT;1;1;-2
SI units	$N$ (Newtons) or $kgm/s^{2}$