# Thrust

on . Posted in Classical Mechanics Thrust or thrust force, abbreviated as F, is a term used in physics and engineering to describe the force that propels an object forward.  It is commonly associated with propulsion systems, such as those used in rockets, jet engines, and other vehicles.

Thrust is generated by expelling or accelerating a mass of fluid or gas in the opposite direction to the desired motion.  According to Newton's third law of motion, for every action, there is an equal and opposite reaction.  In the case of thrust, the action is the expulsion or acceleration of the fluid or gas, and the reaction is the force that propels the object forward.

In rockets, thrust is generated by expelling high speed exhaust gases produced by the combustion of rocket propellant.  Jet engines, on the other hand, generate thrust by drawing in air, compressing it, and then expelling it at high speed through a nozzle.  In both cases, the expelled mass creates a reaction force that propels the vehicle forward.

The magnitude of thrust depends on various factors, including the mass flow rate of the expelled fluid or gas and its velocity relative to the vehicle.  The design and efficiency of the propulsion system also play a significant role in determining the amount of thrust generated.

## Thrust formulas

$$\large{ F = \frac{ \left( m v \right)_2 \;-\; \left( m v \right)_1 }{ t_2 \;-\; t_1 } }$$

$$\large{ F = \frac{ \left( m_2 v_2 \right) \;-\; \left( m_1 v_1 \right) }{ t_2 \;-\; t_1 } }$$

Symbol English Metric
$$\large{ F }$$ = thrust $$\large{ lbf }$$  $$\large{N}$$
$$\large{ m_1 }$$ = initial mass $$\large{ lbm }$$ $$\large{ kg }$$
$$\large{ m_2 }$$ = final mass $$\large{ lbm }$$ $$\large{ kg }$$
$$\large{ t_1 }$$ = initial time $$\large{ sec }$$ $$\large{ s }$$
$$\large{ t_2 }$$ = final time $$\large{ sec }$$ $$\large{ s }$$
$$\large{ v_1 }$$ = initial velocity $$\large{\frac{ft}{sec}}$$ $$\large{\frac{m}{s}}$$
$$\large{ v_2 }$$ = final velocity $$\large{\frac{ft}{sec}}$$ $$\large{\frac{m}{s}}$$ Tags: Force Equations