propulsion
(noun)
 Force causing movement.
Examples of propulsion in the following topics:
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Rocket Propulsion, Changing Mass, and Momentum- In rocket propulsion, matter is forcefully ejected from a system, producing an equal and opposite reaction on what remains.
- The propulsion of all rockets, jet engines, deflating balloons, and even squids and octopuses is explained by the same physical principle: Newton's third law of motion.
- The practical limit for ve is about 2.5×103m/s for conventional (non-nuclear) hot-gas propulsion systems.
 
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Escape Speed- Imagine a situation in which a spaceship that does not have a propulsion system is launched straight away from a planet.
- (It is moot to discuss escape speed for objects with propulsion systems.)
- If the vehicle has a propulsion system to provide it with energy once it has left the surface of the planet, it is not necessary to initially meet escape speed requirements.
 
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Orbital Maneuvers- An orbital maneuver is the use of propulsion systems to change the orbit of a spacecraft (the rest of the flight is called "coasting").
- In spaceflight, an orbital maneuver is the use of propulsion systems to change the orbit of a spacecraft.
 
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Sperm- Motile sperm cells typically move via flagella and require a water medium in order to swim toward the egg for fertilization.These cells cannot swim backwards due to the nature of their propulsion.
 
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Phylum Chordata- In chordates, the tail has skeletal elements and musculature, and can provide most of the propulsion in aquatic species.
 
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Free-Falling Objects- The free fall would end once the propulsion devices turned on.
 
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Classification of Phylum Mollusca- Locomotion in cephalopods is facilitated by ejecting a stream of water for propulsion ("jet" propulsion) .
 
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The Effects of the Cold War- Not only must nuclear weapons and their delivery systems be secured and protected, other nuclear facilities and devices, such as reactors and propulsion systems, must be safeguarded.
 
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Lymphatic Vessel Structure