Thermodynamics
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Thermal Efficiency
A cannon launches a projectile with a mass equal to 1225 kg with a speed of 762 m/s. The projectile is
propelled by a mass of 300 kg of gunpowder, it is known that 1 g of gunpowder burns by producing 1500 cal.
What is the thermal efficiency of this cannon as a heat engine? Assume 1 cal = 4.2 J.
The cylinder of a steam engine receives 2300 kcal per unit of time, of this total 2070 kcal are lost to
the environment. What is the thermal efficiency of this engine?
Work Done by a Gas
A gas undergoes two sucessive processes, first, an isometric process, where it receives 200 joules of heat,
then an isobaric process receiving 150 joules of heat, as show in the figure. Calculate in each process the
work done in the process and the change in internal energy of the gas.
A heat engine works between a high-temperature reservoir at 100 °C and a lower-temperature reservoir at
50 °C, calculate:
a) The thermal efficiency of this machine;
b) The work done by the engine when receiving 10000 kcal of the high-temperature reservoir. Assume 1 cal = 4.2 J.
a) The thermal efficiency of this machine;
b) The work done by the engine when receiving 10000 kcal of the high-temperature reservoir. Assume 1 cal = 4.2 J.
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