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According to Stefan’s law of radiation, a black body radiates energy σ T4 from its unit surface area every second where T is the surface temperature of the black body and σ = 5.67 × 10–8 W/ m2K4 is known as Stefan’s constant. A nuclear weapon may be thought of as a ball of radius 0.5 m. When detonated, it reaches temperature of 106K and can be treated as a black body. (a) Estimate the power it radiates. (b) If surrounding has water at 30 C ° , how much water can 10% of the energy produced evaporate in 1 s?[Sw = 4186.0 J/kgK and Lv = 22.6 x 105 J/kg](c) If all this energy U is in the form of radiation, corresponding momentum is p = U/c. How much momentum per unit time does it impart on unit area at a distance of 1 km? |
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Answer» (i) 1.8 × 1017 J/S (ii) 7 × 109 kg (iii) 47.7 N/m2. |
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