A metal sphere with a black surface and radius `30 min`, is cooled to `-73C (200K)` and placed inside an enclosure at a temperature of `27^(@)C(300K)`. Calculate the initial rate of temperature rise of the sphere, assuming the sphere is a black body. (Assume density of metal `=8000 kg m^(-3)` specific heat capacity of metal `=400 J kg^(-1)K^(-1)`, and Stefan constant `=5.7xx10^(-8)Wm^(-2)K^(-4)`).

A copper cube with sides o flength 20 mm had its surface blackened. The cube is heated up to 500K and placed inside a room at a constant temperature of 300K. Calculate the initial rate of temperature fall of the cube, assuming it as a perfect black-body. (Stefan's constant = 5.7 xx 10^(-8) W//m(2) //K^(4) specific heat capacity of aluminium = 400 J //kg//K , density of aluminium = 7800 kg//m^(3) ) where A is the surface area of the cube, T_(1) is the temperature of the body, and T_(2) is the temperature of the enclosure.

What would be the final temperature of the mixture when 1kg of ice at -10^(@)C is mixed with 4.4kg of water of 30^(@)C ? (Specific heat capacity of ice =2100Jkg^(-1)K^(-1))

A solid copper sphere of dimater 10mm is cooled to temperature of 150K and is then placed in an enclousure at 290K Assuming that all interchange of heat is by radiation, calculate the initial rate of rise of temperature of the sphere The sphere may be treated as a black body rho_(copper) =8.93xx 10^(3)kg//m^(3) s = 3.7xx10^(2) Jkg^(-2) K^(-1) , sigma = 5.7 xx 10^(8) Wm^(-2) K^(-4) .

If the sun's surface radiates heat at 6.3 xx 10^(7) Wm^(-2) . Calculate the temperature of the sun assuming it to be a black body (sigma = 5.7 xx 10^(-8)Wm^(-2)K^(-4))

A solid metallic sphere of diameter 20 cm and mass 10 kg is heated to a temperature of 327^@C and suspended in a box in which a constant temperature of 27^@C is maintained. Find the rate at which the temperature of the Sphere will fall with time. Stefan's constant =5.67xx10^-8W//m^(2)//K^(4) and specific heat of metal =420J//kg//^(@)C .

Certain amount of heat is given to 100 g of copper to increase its temperature by 21^@C . If same amount of heat is given to 50 g of water, then the rise in its temperature is (specific heat capacity of copper = 400 J kg^(-1) K^(-1) and that for water = 4200 J kg^(-1) K^(-1))

A refrigerator converts 1.3 kg of water at 20^(@)C into ice at -15^(@)C in 1 hour. Calculate the effective power of the refrigerator. Specific latent heat of fusion of ice = 3.4 xx 10^(5) J kg^(-1) Specific heat capacity of water = 4.2 xx 10^(3) J kg^(-1) K^(-1) Specific heat capacity of ice = 2.1 xx 10^(3) J kg^(-1) K^(-1)

A black ened metal sphere of radius 7 cm is encllosed in as evacuated chamber maintained at a temperature of 27^(@)C . At what rate must energy be supplied to the sphere so as to keep its temperature constant at 127^(@)C ? sigma=5.7xx10^(-8) W m^(-2) K^(-4) .

Calculate the maximum amount of heat which may be lost per second by radiation by a sphere 14cm in diameter at a temperature of 227^(@)C , when placed in an enclosure at 27^(@)C . Given Stefan's constant = 5.7 xx 10^(-8)Wm^(-2)K^(-4) .