Q. Why will a white roof keep your house cooler in summer than will a black roof?
A. A white roof will reflect more and absorb less heat rays, whereas a black roof will absorb more and reflect less heat rays. Hence, a white roof will keep the house cooler in summer.
Q. Why is it hotter on a cloudy covered night than in a clear night ?
A. Because clouds prevent the heat radiated out by the earth from escaping into the sky. As this heat remains in the atmosphere, the cloudy nights are warm in comparison to clear nights.
taken away which results in lowering the temperature of the sick person. Thus eau-de-cologne helps to bring down the body temperature and provides relief to the sick person.
Q. Why does the water in an open pond cool even on a burning hot day ?
A. This is due to the fact that cooling is caused by evaporation.
Q. Why are metal tyres of cart wheels fitted when hot ?
A. Metal (iron) tyre is heated strongly. On heating tyre expands and the circumference of the tyre becomes slightly bigger than the wooden wheel. This permits the easy slipping of the tyre on wooden wheel. Thereafter, cold water is poured over the metal tyre and it shrinks in size. Therefore, its circumference fits the wheel well and holds on tightly.
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