Q # 1 A cube of cooper 2.00cm on a side is suspended by a string. The cube is he

Question

Q # 1

A cube of cooper 2.00cm on a side is suspended by a string. The cube is heated with a burner from 20.0C to 90.0C. The air surrounding the cube is atmospheric pressure (1.01 × 105Pa). Find

a)      The increase in volume of the cube;

b)      The mechanical work done by the cube to expand against the pressure of the surrounding air;

c)      The amount of heat added to the cube;

d)     The change in internal energy of the cube.

Note: For Copper = 5.1 × 10-3 (C)-1 Cp = 390J/Kg.K & (Rho) = 8.90 × 103Kg/m3

Q # 2

A freezer has a coefficient of performance of 2.40. The freezer is to convert 1.80Kg of water at 25.0C to 1.80kg of ice at -5.0C in hour.

a)      What amount of heat must be removed from the water at 25.0 C to convert it to ice at -5.0C?

b)      How much electrical energy is consumed by the freezer during this hour?

c)      How much wasted heat is delivered to the room in which the freezer sits?

Note that for water Cw = 4190J/Kg.K, Lf = 3.34 × 105J/Kg.K & Cice = 2010J/Kg.K

Explanation / Answer

a) given For Copper = 5.1 × 10-3 (C?)-1 Cp = 390J/Kg.K & (Rho) = 8.90 × 103Kg/m3 side of the cube L = 2.0cm = 0.02m volme of the cube V0 = L3 = (0.02m)3 side of the cube L = 2.0cm = 0.02m volme of the cube V0 = L3 = (0.02m)3 increase in volume is               V = V0 T                       =5.1 × 10-3 (C?)-1 ((0.02m)3(900 - 200)                        = 2.86* 10-8 m3 b)W = pV ( since applied pressure is air pressure )         = 1.013* 105 pa (2.86* 10-8 m3)          = 2.88* 10-3 J c)Q = mcp T        = V0 cp T         = 8.90 × 103Kg/m3 (0.02m)3 (390J/Kg.K)(70)         =1944J d) from teh figures U = Q = 1940J according to cramster rules only one post to be answer so please send second question in the next post I will answer you thank u b)W = pV ( since applied pressure is air pressure )         = 1.013* 105 pa (2.86* 10-8 m3)          = 2.88* 10-3 J c)Q = mcp T        = V0 cp T         = 8.90 × 103Kg/m3 (0.02m)3 (390J/Kg.K)(70)         =1944J d) from teh figures U = Q = 1940J according to cramster rules only one post to be answer so please send second question in the next post I will answer you thank u

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