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Chapter 14: Q27Q (page 390)

An “emergency blanket” is a thin shiny (metal-coated) plastic foil. Explain how it can help to keep an immobile person warm.

Short Answer

Expert verified

The net heat loss from the blanket is less due to the low emissivity of the shiny metal-coated emergency blanket. The blanket also prevents heat loss by convection and conduction.

Step by step solution

01

Understanding the heat loss reduction by the emergency blanket

The blanket, which is shiny and plastic coated, works as an insulator and reduces heat loss by conduction. It also prevents the loss of energy by convection. The heat radiated by the person's body reflects onto the person. It thus saves the loss of heat energy.

02

Explanation for how the blanket helps to keep an immobile person warm.

The emergency blanket having shiny metal-coated plastic foil has a low value of emissivity factor. So, the net heat transfer from the person's body to the outside surrounding will be very less.

The heat radiated by the body strikes the blanket and then returns to the person's body. Due to this, there is very less amount of heat loss from the blanket. It acts as an insulator and prevents heat transfer by the process of conduction and convection.

So, the blanket helps an immobile person to stay warm inside it.

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FIGURE 14-20

Problem 47.
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