During summers in India, one of the common practices to keep cool is to make ice balls of crushed ice, dip it in flavored sugar syrup and sip it. For this a stick is inserted into crushed ice and is squeezed in the palm to make it into the ball. Equivalently in winter, in those areas where it snows, people make snow balls and throw around. Explain the formation of ball out of crushed ice or snow in the light of P–T diagram of water.
The process of making an ice ball deals with interconversion of the states of water.
While making an ice ball, we apply pressure on the crushed ice. The temperature is 0°C and the atmospheric pressure is 1 atm. Increasing this pressure shift the state from solid to liquid as indicated by the circle. Due to this, a part of the crushed ice melts and fills any gaps present in between ice flakes. When we release pressure, the water again solidifies to ice thus making the ice ball.
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Calculate the temperature which has same numeral value on Celsius and Fahrenheit scale.Physics - Exemplar
According to Stefan’s law of radiation, a black body radiates energy σT 4 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?
Physics - Exemplar
100 g of water is supercooled to –10° C. At this point, due to some disturbance mechanized or otherwise some of it suddenly freezes to ice. What will be the temperature of the resultant mixture and how much mass would freeze?
[Sw = 1 cal/g/° C and Lw fusion = 80 cal/ g]
Physics - Exemplar
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During summers in India, one of the common practices to keep cool is to make ice balls of crushed ice, dip it in flavored sugar syrup and sip it. For this a stick is inserted into crushed ice and is squeezed in the palm to make it into the ball. Equivalently in winter, in those areas where it snows, people make snow balls and throw around. Explain the formation of ball out of crushed ice or snow in the light of P–T diagram of water.Physics - Exemplar
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an optical pyrometer (for measuring high temperatures) calibrated for an ideal black body radiation gives too low a value for the temperature of a red hot iron piece in the open, but gives a correct value for the temperature when the same piece is in the furnaceNCERT - Physics Part-II
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Given below are observations on molar specific heats at room temperature of some common gases.
The measured molar specific heats of these gases are markedly different from those for monatomic gases. Typically, molar specific heat of a monatomic gas is 2.92 cal/mol K. Explain this difference. What can you infer from the somewhat larger (than the rest) value for chlorine?NCERT - Physics Part-II
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