Convection works by transferring heat from a hot substance to a cooler one through the motion of one of the substances. For example, as wind passes over a hot substance, heat from the substance transfers to the air particles, cooling the hot substance and slightly warming the air.Know More
Convection is effective because the continuous flow of the cooler substance allows for continued heat transfer. Because the movement is so important for convection, consideration of convection currents, which describe the patterns of movement of the substances, helps provide a detailed description of the effect.
Two broad types of convection exist: spontaneous convection and forced convection. Spontaneous convection occurs when the convection currents arise naturally. For example, winds moving from cooler to warmer areas naturally cool the surfaces they pass over. Ocean currents are another form of spontaneous convection; the flow of water in the ocean leads to heat transfer for different land masses, and it cools water emerging from deep ocean heat vents.
Forced convection occurs when the cooling substance is propelled along the surface of the hotter substance or vice versa. For example, during beer brewing, many breweries force large quantities of cold water through copper pipes that make contact with boiling wort; this leads to rapid temperature drops in the wort, speeding the brewing process.Learn more about Motion & Mechanics
Most automotive oil coolers pass heated oil through a radiator-type device equipped with a fan that forces air through coils to dissipate heat, explains About.com. Some systems prevent oil overheating by constantly forcing water or liquid coolant through a maze of tubes. Viscosity is drastically reduced in overheated oil, reducing lubricating efficiency and engine performance.Full Answer >
Convection occurs in fluids that are heated. Warm fluid molecules are able rise, due to their lower density, while the cooler molecules sink. This cyclic movement of hot and cold molecules, due to differences in density, causes convection currents, aiding in heat circulation.Full Answer >
Convection currents occur due to the density difference between hot and cold fluids. A fluid that is heated from below expands and rises. When this fluid becomes cool, it contracts and sinks. This continuous cycle of expansion and contraction causes convection cells.Full Answer >
In roller coasters, friction is a force that opposes motion and significantly slows the cars as they move on the track. While it is easy to believe that friction is bad for the ride, it is one of the forces engineers consider in ensuring passengers have a safe ride.Full Answer >