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hanjy85

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## Homework Statement

A thin sheet of ice with an area of 0.15m^2 on each side hangs from a roof.

The ice is at 0C (Celsius) and the surrounding air is at 10C.

The net rate at which radiant energy is transferred to the ice from the sunlight and

from the surroundings is 20W; q=9.5W*m^-2*K^-1

What mass of ice melts in 1 minute?

## Homework Equations

Heat trasfer by convection: H=qAΔT (A: surface area)

Latent heat for phase change: ΔQ=Lm (L:latent heat, specific to material, m=mass)

## The Attempt at a Solution

I'm in trouble. The correct answer is 8.74X10^-3kg but me and all of my classmates failed to get the correct answer. And I don't know why q is provided in the question. Do I really need that to solve this problem?

Anyways, this is my attempt to solve the problem.

The net rate at which radiant energy is transferred to the ice = 20W (J/s)

Thus, in 1 minute = 20Wx60sec=1200J=The heat ΔQ provided to change the phase of ice.

(solid to liquid)

Latent heat of fusion (water) = 333KJ/kg required (solid to liquid)

Therefore, 1200J=(333Kj/kg)*m

m=0.003604kg

or this:

the heat transferred from surrounding area to the sheet of ice:

H = qAΔT = (9.5W*m^-2*K^-1)(0.3m^2)(10k)=14.25W

in 1 minute = 14.25Wx60sec=855J

Latent heat of fusion (water) = 333KJ/kg (solid to liquid)

Therefore, 855J=(333Kj/kg)*m

m=0.002567kg

please tell me what I did wrong. Thanks a lot and have a nice day :D