# Thermodynamics Essay Example

Pressure due to 2kg mass = This pressure is transmitted to the bigger piston generating a for =pxA =25.5×12=25.5N

This is counterd by the pressure due to 8kg mass= This two pressures are equal a clear indication of equilibrium

No. Because we have varying temperature levels in the system (20 and 15C)

This system has only water as the medium and thus there is no phase equilibrium

No because there is a temperature difference in the system

Heat absorbed by water = Mass x change in temperature xspecific heat capacity of water

Heat absorbed= 1x75x4.2=315Kj

PE=mgLsin =40×9.8x10sin2=136.8o6

Potential energy is slightly higher

From Q5 Power= Energy/Time=315/120=2.625kW

Energy=mass x heat of vaporization of water =0.5×2257=1128.5Kj

Time =Energy/Power=1128.5/2.625=430s= 7 min 10s

Energy absorbed by water =315

Actual energy to be supplied =315/0.75=420Kj

If 1kg supplies 45000kj

For 420Kj=420/45000×1= 0.0093kg of natural gas

Q.8 Express 42.19 C as an absolute temperature accurate to two decimal places.

T(K)=T(C )+273.15= 42.19+273.15=315.34K

This is an open system because there is both exchange of heat energy and mass across the system boundary

Isobric since the pressure remains constant

Isothemal process

Isochoric since volume is kept constant Pg=Patm+   Pg=Patm+   Power= Tω= =549.8w=0.5498kw

Work done = Pt=0.5498x20x60= 659.76kJ

W=RI2t= 1200×2.52x600=4500kJ

pressure (abs)= 101+95×6.89475= 756kpa  Power generated by one turbine= 0.25×47.33= 11.83kw

Total kWh generated by 1 turbine per year= 11.83x365x24=103630.8kwh

Total kwh consumed by 200houses=6000×200= 1200000kwh

Therefore number of turbines =1200000/103630=11.6

Which means 12 turbines will be required.