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propel

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Definition

Propel has a few different meanings in science. In physics, it refers to the act of applying a force to an object in order to cause it to move. In engineering, it refers to the design and construction of devices that propel objects, such as rockets, engines, and propellers.

In physics, the force that propels an object is called the thrust. The thrust is equal to the mass of the object multiplied by its acceleration. Acceleration is the rate at which the object's velocity changes.

In engineering, the design of a propulsion system is based on the following factors:

  • The mass of the object that needs to be propelled
  • The desired velocity of the object
  • The available fuel
  • The environmental conditions in which the object will be propelled

The most common types of propulsion systems are:

  • Rocket propulsion: Rockets use fuel and oxygen to create hot gases that propel the rocket forward.
  • Jet propulsion: Jet engines use fuel and air to create hot gases that propel the jet forward.
  • Propeller propulsion: Propellers use rotating blades to move air past them, which creates thrust.

How can the word be used?

The swimmer propelled himself through the water.

propel

Different forms of the word

Verb: to drive or force something forward.

Noun: the act of propelling something.

Etymology

The word "propel" comes from the Latin word "propellere", which means "to drive forward".

The first recorded use of the word "propel" in English was in the 14th century.

Question

What things might propel?

AQA Science Exam Question and Answer

Question:

Explain the concept of propulsion in the context of physics and provide examples of how it is applied in everyday situations. Discuss the basic principles behind propulsion and how they relate to Newton's third law of motion.

Answer:

Propulsion in physics refers to the action of generating force to push or drive an object forward. It involves expelling mass in one direction, which results in the object moving in the opposite direction due to Newton's third law of motion, often summarised as "for every action, there is an equal and opposite reaction.".

Everyday situations provide numerous examples of propulsion. A rocket launching into space, a car accelerating on the road, or a person swimming are instances where propulsion is at play. Rockets expel high-speed exhaust gases, cars utilise engines and wheels, and swimmers use arm and leg movements to push against the water, all resulting in forward motion.

The basic principle behind propulsion is the conservation of momentum. When an object expels mass at a certain speed, it experiences an equal but opposite force, causing it to move in the opposite direction. This relationship exemplifies Newton's third law, showcasing how action and reaction are interconnected.