The change in internal energy during one complete cycle of a heat engine a. equals the net heat flow into the engine. b. equals zero. c. equals the heat energy exhausted from the engine. d. equals the heat energy entering the engine.

B. equals zero

Explanation:

Given data

one complete cycle = heat flow

solution

we have given that when heat engine complete 1 cycle change in energy = net heat flow

that is always equal to zero

from first law of thermodynamics that

ΔU = Q + W

we know ΔU is the change internal energy in system and Q is net heat transfer in system and W is  net work done in system

therefore change of internal energy during one cycle

ΔU = Ufinal -  Uinitial

ΔU  = Uinitial  -  Uinitial  = 0

as we know our atmosphere or air have different levels. every level has other gasses, and every gas has another permeability. when the light comes from lower permeability to higher permeability, it changes its direction. so that means that when the light comes from the moon to the earth, it changes it's direction many more times. it basically means that the shape of the light part of the moon is changed on the earth.

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