Afreezer compartment is covered with a 2-mm-thick layer of frost at the time it malfunctions. if the compartment is in ambient air at 20 °c and a coefficient of h 2 w/(m2 k) characterizes heat transfer by natural convection from the exposed surface of the layer, estimate the time required to completely melt the frost. the frost may be assumed to have a mass density of 700 kg/m3 and a latent heat of 334 kj/kg.

The time required to melt the frost is 3.25 hours.

Explanation:

The time required to melt the frost dependes on the latent heat of the frost and the amount of heat it is transfered by convection to the air .

The heat transferred per unit area can be expressed as:

being hc the convective heat transfer coefficient (2 Wm^-2K^-1) and ΔT the difference of temperature (20-0=20 °C or K).

If we take 1 m^2 of ice, with 2 mm of thickness, we have this volume

The mass of the frost can be estimated as

Then,  the amount of heat needed to melt this surface (1 m²) of frost is

The time needed to melt the frost can be calculated as

a chemical reaction

explanation:

answer

fusion: the energy source of stars. the energy released from the collapse of the gas into a protostar causes the center of the protostar to become extremely hot. when the core is hot enough, nuclear fusion commences. fusion is the process where two hydrogen atoms combine to form a helium atom, releasing energy.

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