Thrust

Definition

Thrust is the force applied on a surface in a direction perpendicular or nearly perpendicular to that surface. It often results from the expulsion of mass, as seen in rockets and jet engines.

5 Must Know Facts For Your Next Test

1. Thrust is directly related to Newton's Third Law: for every action, there is an equal and opposite reaction.
2. In rocketry, thrust is generated by expelling exhaust gases at high speed in the opposite direction.
3. The magnitude of thrust can be calculated using $F = ma$, where $F$ is the thrust force, $m$ is the mass flow rate, and $a$ is the acceleration of the exhaust gas.
4. Airplanes use jet engines or propellers to generate thrust to overcome drag and achieve forward motion.
5. Thrust must overcome both gravitational forces and drag for a rocket or aircraft to accelerate.

Review Questions

• How does Newton's Third Law explain the generation of thrust in a rocket?
• What are two primary sources of thrust in aviation?
• How can you calculate the magnitude of thrust using mass flow rate and exhaust velocity?

Related terms

Newton's Third Law:

States that for every action, there is an equal and opposite reaction.

Drag: The resistance force caused by the motion of a body through a fluid (such as air).

Lift: The force that directly opposes the weight of an airplane and holds it in the air.