![]() ![]() During perspiration, sweat removes heat from the human body by evaporating. In machining, water and oils are used to remove the excess heat generated, which can quickly ruin both the work piece and the tooling. Liquid propellant films are used to cool the thrust chambers of rockets. The coolants used in nuclear reactors include water or liquid metals, such as sodium or bismuth. Water or glycol coolants are used to keep engines from overheating. The heat can be removed by channeling the liquid through a heat exchanger, such as a radiator, or the heat can be removed with the liquid during evaporation. Liquids tend to have better thermal conductivity than gases, and the ability to flow makes a liquid suitable for removing excess heat from mechanical components. They are used in the food industry, in processes such as the extraction of vegetable oil. They are found in cosmetics, inks, and liquid dye lasers. Solvents like alcohol are often used as antimicrobials. Surfactants are commonly found in soaps and detergents. Naphtha and acetone are used frequently in industry to clean oil, grease, and tar from parts and machinery. Solutions are found in a wide variety of applications, including paints, sealants, and adhesives. Many liquids are used as solvents, to dissolve other liquids or solids. Oils are often used in engines, gear boxes, metalworking, and hydraulic systems for their good lubrication properties. Lubricants such as oil are chosen for viscosity and flow characteristics that are suitable throughout the operating temperature range of the component. In tribology, liquids are studied for their properties as lubricants. ![]() We call this the density and it is different for all liquids. ![]() ρ is a number that tells us how heavy a set amount of the liquid is. Where z is the depth of the point below the surface and g is how strong gravity is pulling on the liquid. The equation for working this out is: p = ρgz In a liquid, the liquid on the top presses down on the liquid underneath, so at the bottom the pressure, p, is bigger than at the top. The boiling point of water is 100☌, at this temperature it becomes steam.Įxamples of liquid are water, oils and blood. The temperature this happens at is called the boiling point. If a liquid is heated up it becomes a gas. The freezing point of water is around 0☌, and it becomes ice. This temperature is called the melting point and is different for every different type of liquid. If a liquid is cooled down until it is colder than a certain temperature, it will become a solid. Some fluids like tar have such a high viscosity that they may seem solid. The molecules that make up the liquid can freely move among themselves.įluids that flow slowly have a high viscosity. Because of that, gravity makes liquids always take the shape of the container. Liquid has an almost-fixed volume, but no set shape.Įvery small force makes a liquid change its shape by flowing. ![]()
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