- #1
bubuchnik
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Homework Statement
1. An ideal gas with a molar mass of 40*kg/kmol and a specific heat ratio k*=*1.67 receives an amount of heat per unit mass equal to 10*kJ/kg. Calculate the resultant temperature rise if ,
a) The heat is added at constant volume
b) The heat is added at constant pressure
2. Hydrogen is contained in a piston-cylinder device at 100 kPa and 1 m3. At this state, a linear spring (F proportional to x) with a spring constant of 200 kN/m is touching the piston but exerts no force on it. The cross-sectional area of the piston is 0.8 m2. Heat is transferred to the hydrogen, causing it to expand until its volume doubles. Determine (a) the final pressure, (b) the total work done by the hydrogen and (c) the amount of work done against the spring. Also show the process on a p-V diagram.
If i knew the equations and the how to even attempt these i would post them. But I'm truly stumped ! :(
Any help would be appreciated. Thank you...
EDIT: If you really need to see some work before you can help...
1)For the first one i tried applying q=mc(delta)t
And since c for constant volume is 12.41 (k= cv/cp)
I'm getting (delta)t as around 20. But the answer says 32.3
And following the same process for constant pressure I'm gettin about 12 but the answer says 19.3
2) I tried to find the final pressure first. And i did p1/p2=v1/v2 and since the volume doubles p2 should be 50 kpa. But the answer says 412.5 kpa. Since the rest of it depends on this i didn't try further.
I know I'm missing something big here.
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