Thrust

Thrust is the force used to accelerate an object by expelling gas molecules at high speeds. This is the principle operation behind a jet engine. In a mechanical system, such as a rocket, an engine or turbine will do work to send gas molecules downwards. By Newton's Third Law, a force will be felt in the opposite direction of molecule travel and the system will feel a force upwards. This upwards force is thrust. (see Figure 1). Jet engines expel a jet of a fluid and the momentum of that jet pushes the object forward.

Visit NASA to learn more about propulsion systems and thrust.

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  Figure 1. Thrust is derived from Newton's 3rd law—every action has an equal and opposite reaction.
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  Figure 2. A rocket uses thrust to overcome the gravitational forces on Earth's surface.

For Further Reading

For further information please see the related pages below:

• Force
• Law of conservation of energy
• Work
• Kinetic energy
• Engine
• Or explore a random page