1. A certain diet doctor encourages people to diet by drinking ice water. His th

Question

1. A certain diet doctor encourages people to diet by drinking ice water. His theory is that the body must burn off enough fat to raise the temperature of the water from 0.00°C to the body temperature of 37.0°C. How many liters of ice water would have to be consumed to burn off 280 g (about 0.617 lb) of fat, assuming that this much fat burning each gram of fat requires 7.71 Cal be transferred to the ice water? (One liter = 10-3m3. The density of water is 1.00 g/cm3.)

2. The ceiling of a single-family dwelling in a cold climate should have an R-value of 45 ft2 ·F°·h/Btu. To give such insulation, how thick would a layer of (a) polyurethane foam and (b) silver have to be? The thermal conductivity of polyurethane foam is 0.024 W/m·K, and the thermal conductivity of silver is 428 W/m·K.

Explanation / Answer

(1)

280g x 7.71 cal

2158.8 cal in total

2158.8(Q) = (m) g[1 g/cal (c)] [310K - 273K(dT)]

2158.8/37 = 58.34... so 58.34 grams of water

where d = m/V or V = m/d where density = 1

V = 58.34cm3 or 5.834 m3 or 5.834 L ans

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