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lubricant

Primary Information
Secondary Information

Definition

A lubricant is a substance that reduces friction and wear between two surfaces in contact. It can be a liquid, solid, or gas.

Lubricants work by forming a film between the two surfaces. This film helps to separate the surfaces and prevent them from touching each other directly. This reduces the friction between the surfaces and also helps to protect them from wear.

Lubricants are used in many different machines and devices. For example, they are used in cars, engines, and bicycles. They are also used in industries such as mining, manufacturing, and construction.

Here are some of the properties of a good lubricant:

  • Low viscosity: A good lubricant should have low viscosity, which means that it should flow easily. This allows it to form a thin film between the two surfaces, which reduces friction.
  • High shear strength: A good lubricant should have high shear strength, which means that it should not easily break down under pressure. This is important for machines and devices that operate under high loads.
  • Chemical stability: A good lubricant should be chemically stable, which means that it should not react with the materials that it is used with. This is important to prevent the lubricant from breaking down and causing damage to the machine or device.
  • Corrosion protection: A good lubricant should also have corrosion protection properties. This is important to prevent the lubricant from corroding the materials that it is used with.

How can the word be used?

The machine needs to be lubricated regularly to prevent it from overheating.

lubricant

Different forms of the word

Noun: A substance that is used to reduce friction between two surfaces.

Verb: To apply a lubricant to something.

Adjective: Describing something that is slippery or oily.

Etymology

The word "lubricant" comes from the Latin word "lubricare", which means "to make slippery". It was first used in English in the 15th century.

The Latin word "lubricare" is derived from the Proto-Indo-European root *leubh-, which means "to grease". This root is also the source of the English words "oil" and "grease".

Question

What is lubricant used for?

AQA Science Exam Question and Answer

Question:

Explain the role of a lubricant in reducing friction and enhancing mechanical efficiency in machines. Provide an example to illustrate its importance.

Answer:

A lubricant is a substance used to reduce friction between moving surfaces in machines, engines, or mechanical systems. Friction is the force that opposes the relative motion of surfaces in contact, leading to energy loss and wear. Lubricants play a vital role in minimising friction, enhancing mechanical efficiency, and extending the lifespan of components.

When two surfaces come into contact, the irregularities on their surfaces can create friction, generating heat and causing wear and tear. A lubricant forms a protective layer between these surfaces, reducing the direct contact between them. This layer prevents metal-to-metal contact and allows for smoother movement, which in turn reduces frictional forces. As a result, the amount of heat generated and the wear on the surfaces are significantly reduced, leading to improved efficiency and longevity of the machine.

For instance, in automobile engines, motor oil acts as a lubricant. It coats the engine's moving parts, such as pistons and bearings, preventing excessive friction and heat buildup. This allows the engine to operate smoothly and efficiently, while also reducing the risk of damage due to wear.