Topher Posted September 28, 2011 Posted September 28, 2011 1. 0.01kg of air is compressed in a cylinder so that the temperature of the air rises from 293K to 413k if the work done is 2000J, calculate the heat flow ... 2. if the air in the cylinder is now allowed to cool to 293K again, while the same cylinder volume is maintained, calculate the additional heat flow ... so for #1 known values are Delta T=120 M=0.1 Q=2000 ... #2 Delta T = -120 M=0.1 and volume stays constant ... also for all of the questions air: Cv=718J/kgK Cp=1005J/kgK R-287J/kgK I've managed to get myself stuck I don't know which formula is needed to solve this problem, or maybe it's just I don't know the symbol for heat flow, thanks for the help
Schrödinger's hat Posted September 28, 2011 Posted September 28, 2011 1. 0.01kg of air is compressed in a cylinder so that the temperature of the air rises from 293K to 413k if the work done is 2000J, calculate the heat flow ... 2. if the air in the cylinder is now allowed to cool to 293K again, while the same cylinder volume is maintained, calculate the additional heat flow ... so for #1 known values are Delta T=120 M=0.1 Q=2000 ... #2 Delta T = -120 M=0.1 and volume stays constant ... also for all of the questions air: Cv=718J/kgK Cp=1005J/kgK R-287J/kgK I've managed to get myself stuck I don't know which formula is needed to solve this problem, or maybe it's just I don't know the symbol for heat flow, thanks for the help W is work, Q is heat. Usually you'll use: [math] \Delta U = W + Q [/math] Where W is the work done and Q is the heat flow. Which says the change in the internal energy is the work done on the system plus the heat put into it.
Schrödinger's hat Posted September 28, 2011 Posted September 28, 2011 Ok, what is delta U? Change in internal energy 1
mississippichem Posted September 28, 2011 Posted September 28, 2011 Are we assuming diathermic boundaries here? The question as posted is a bit ambiguous I think.
Topher Posted October 1, 2011 Author Posted October 1, 2011 Are we assuming diathermic boundaries here? The question as posted is a bit ambiguous I think. In the first question .. no. In the second question of course, the air is ''allowed to cool''.
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