When the air temperature is below 0 ?C, the water at the surface of a lake freez

Question

When the air temperature is below 0 ?C, the water at the surface of a lake freezes to form a sheet of ice.

Part A

If the upper surface of an ice sheet 24.0 cm thick is at -10.0 ?C and the bottom surface is at 0.00 ?C, calculate the time it will take to add 2.00 mm to the thickness of this sheet.

8832

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When the air temperature is below 0 ?C, the water at the surface of a lake freezes to form a sheet of ice.

Part A

If the upper surface of an ice sheet 24.0 cm thick is at -10.0 ?C and the bottom surface is at 0.00 ?C, calculate the time it will take to add 2.00 mm to the thickness of this sheet.

8832

SubmitMy AnswersGive Up

Incorrect; Try Again; 4 attempts remaining; no points deducted

Not quite. Check through your calculations; you may have made a rounding error or used the wrong number of significant figures.

Explanation / Answer

Data:

Density of ice, = 0.92 g/cc

Additional thickness, L = 0.2 cm

Thickness, x = 24 cm

Latent heat of ice, Lf = 80 cal/g

Thermal conductivity of ice, k = 0.004 cal /s.cm.deg C

Change of temp, = 10 deg C

Solution:

Rate of heat conduction, Q/t = k A / L ...(1)

Heat required for change of state, Q = m Lf

                                                        = V Lf

                                                        = A x Lf ...(2)

From (1) and (2)

k A t / L = A x Lf

t = x Lf L / k

= 0.92 * 24 * 80 * 0.2 / ( 0.004 * 10 )

= 8833 s

Ans:

Time, t = 8833s

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