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                                    A sample of ideal gas `(gamma = 1.4)` is heated at constant pressure. If `140 J` of heat is supplied to gas, find `DeltaU` and W`. | 
                            
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Answer» Suppose the sample contains n moles. Also, suppose the volume changes from `V^(1) to V^(2)` and the temperature changes from `T^(1) to T^(2)`. The heat supplied is `DeltaQ = nCp(T^(2) -T^(1))`. (a) The change in internal energy is `DeltaU = nCv (T^(2) - T^(1)) = Cv / Cp nCP (T^(2) - T^(1))` `= Cv / Cp DeltaQ = 140 J / 1.4 = 100 J`. (b) The work done by the gas is `DeltaW = DeltaQ - DeltaU 140 J - 100 J = 40 J`.  | 
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