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प्रश्न
Explain, why does a wise farmer water his fields, if forecast is forst?
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उत्तर
The frost can seriously damage the leaves and fruit of plants. When a farmer waters his fields, during, night, this water gives large amount of heat energy, because 1 g of water will liberate 4.2 J of energy for every 1°C fall in temperature. Thus, the air around the field is saturated with heat energy and its temperature does not fall below 0°C. Thus, no frost is formed.
संबंधित प्रश्न
Calculate the mass of ice required to lower the temperature of 300 g of water 40°C to water at 0°C.
(Specific latent heat of ice = 336 J/g, the Specific heat capacity of water = 4.2J/g°C)
What do you understand by the following statements:
The specific heat capacity of lead is 130 Jkg-1K-1.
What do you mean by the following statement?
The specific heat capacity of copper is 0. 4 Jg-1 K-1?
Without green house effect, the average temperature of earth’s surface would have been:
(a) – 18℃
(b) 33℃
(c) 0℃
(d) 15℃
A calorimeter has mass 100 g and specific heat 0.1 kcal/ kg°C. It contains 250 gm of liquid at 30°C having specific heat of 0.4 kcal/kg°C. If we drop a piece of ice of mass 10 g at 0°C, What will be the temperature of the mixture?
Give one example where high specific heat capacity of water is used as cooling.
The product of mass and specific heat is known as ..........
A liquid X has specific heat capacity higher than the liquid Y. Which liquid is useful as heat reservoir to keep juice bottles without freezing?
m kg of a substance of specific heat capacity s J/kg °C is heated so that its temperature rises from θ1°C to θ2°C. Write down the expression for the heat Q supplied.
How much heat energy is released when 5 g of water at 20° C changes to ice at 0° C?
[Specific heat capacity of water = 4.2 J g-1 ° C-1 Specific latent heat of fusion of ice = 336 J g-1]
