A thin plastic blanket, with a shiny metallic surface, is wrapped a walker who has collapsed after a steep climb. Which type of heat loss is the shiny surface intended to reduce?
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Radiation
The shiny metallic surface of the thin plastic blanket is intended to reduce heat loss by a process called radiation.
To understand this phenomenon, let's first talk about the different modes of heat transfer. Heat can be transferred through three different modes: conduction, convection, and radiation.
Conduction occurs when heat is transferred through direct contact between objects that have different temperatures. For example, if you touch a hot object, such as a stove, the heat is conducted from the stove to your hand.
Convection, on the other hand, is the transfer of heat through a fluid medium, such as air or water. For instance, when you heat a room with a heater, the warm air rises, creating a convection current that circulates the heat around the space.
Lastly, radiation is the transfer of heat through electromagnetic waves. Unlike conduction and convection, radiation does not require a medium to carry heat. Instead, it can travel through empty space. When an object emits heat in the form of electromagnetic waves, it is said to radiate heat.
In the scenario you described, the shiny metallic surface of the plastic blanket is designed to reduce heat loss by reflection. The shiny surface reflects a significant portion of the radiation emitted by the walker's body back towards them. By doing so, it minimizes the amount of heat that is lost to the surroundings through radiation.
To summarize, the shiny metallic surface of the plastic blanket reduces heat loss through radiation by reflecting the body's emitted heat back towards the walker, helping them retain more warmth.