Thermodynamics Questions and Answers

A heat engine has the three step cycle shown above. Starting from point A, 1 L (liter) of an ideal gas expands in an isobaric (constant pressure) process from A to B at a pressure of P = 2 atm. B to C is an isochoric process (constant volume) at a volume of V = 5 L, and C to A is an isothermal (constant temperature) compression at a temperature of 300 K. a) Find the pressure (in atm) at point C. b) Suppose that the internal energy of the gas as a function of temperature is given by U(T) = 5.0 J/K X T. Find the energy exhausted as heat in the process from B to C. c) Suppose the net work done by the engine per cycle is 480 J. Find the work done by the gas during the process from C to A.

In an adiabatic compression, 0.10 m³ of a monoatomic gas at 400.0 K is brought to 535.0 K. What is the volume of the heated gas? 0.065 m³ 0.082 m³ 0.15 m³ Cannot be calculated without pressure

The gas in a cylinder expands and forces a piston outward. During this process, the gas has a constant pressure of 3.15x105 Pa. The volume in the cylinder changes from 9.60x10-4 to 1.00x10-3 m³. The work done on the gas is... 12.6J -303J 315J -12.6J

A nuclear power plant operates at 69 % of its maximum theoretical (Carnot) efficiency between temperatures of 665 °C and 310 °C. If the plant produces electric energy at the rate of 1.6 GW, how much exhaust heat is discharged per hour? Express your answer using two significant figures.

1.5 kg of water at 27 °C is mixed with 1.5 kg of water at 60 °C in a well-insulated container. Estimate the net change in entropy of the system. Express your answer to two significant figures and include the appropriate units.

A dead body was found within a closed room of a house where the temperature was a constant 70° F. At the time of discovery the core temperature of the body was determined to be 85° F. One hour later a second measurement showed that the core temperature of the body was 80° F. Assume that the time of death corresponds to t = 0 and that the core temperature at that time was 98.6° F. Determine how many hours elapsed before the body was found. [Hint: Let t₁ > 0 denote the time that the body was discovered.] (Round your answer to one decimal place.)

P-V diagram of an ideal diatomic gas is a straight line passing through origin. The molar heat capacity of the ideal gas in the process is n times the molar heat capacity of gas at the constant volume. Find the value of n.

A gas inside a piston-cylinder assembly undergoes a refrigeration cycle consisting of these three processes: Process 1-2: Compression with pV = constant from p₁ = 1 bar, V₁ = 1 m³, to p₂ = 10 bar, V₂ = 0.1 m³. Process 2-3: Constant volume heating until P3 = P₁. Process 3-1: Constant-pressure, adiabatic expansion. There are no changes in kinetic or potential energy. a) [3 pts] Find the work for process 1-2 in kJ. b) [3] Find the work for process 2-3 in kJ. c) [3] Find the work for process 3-1 in kJ. d) [2] Find the net work for the entire cycle in KJ. e) [3] Find the net heat transfer for the entire cycle, in kJ. f) [3] Find the heat transfer for process 3-1 in kJ. g) [3] Knowing Q12 = -100 kJ, find the heat transfer for process 2-3 in kJ.

Explain the energy flow in a heat engine with a neat labelled diagram and define the thermal efficiency of a heat engine.

2 moles of an ideal gas is taken through a process for which the variation of internal energy (U) is shown in the figure. Temperature at points A and Care 500 K and 300 K respectively. Work done by the gas in complete process is nearly (In 2 = 0.7) 1100 J 3700 J 2300 J 2800 J

A 1.00-L insulated bottle is full of tea at 90.0°C. You pour out one cup of tea and immediately screw the stopper back on the bottle. Make an order-of-magnitude estimate of the change in temperature of the tea remaining in the bottle that results from the admission of air at room temperature. State the quantities you take as data and the values you measure or estimate for them.

According to Einstein's equation E = mc². E represents the rest mass energy of an object with rest mass m, c is the speed of light in vacuum, and is given by 2.998 × 10^8 m/s . Find the rest mass energy of electron whose rest mass is 9.11 × 10^-31 kg

What is the best coefficient of performance for a heat pump with a hot reservoir of 50°C and a cold reservoir of -20°C? b. How much heat transfer occurs into the warm environment if 3.6*107 J of work is put into the system? c. If the cost of this work is 25 cents per 107 J of work, what would be the cost for the heat cost for the heat in part b? d. How would this cost compare to burning natural gas directly for heat (not a heat pump) if that work cost 8 cents per 10^7 J of work?

The diagram shows a generic heat pump operating between two temperature reservoirs. Here are the values for the variables indicated in the graphic: TH=615 K TL = 316 K QH=9550 J QL=1230 J Answer the three parts below, using three sig figs. How much work, W, is performed by this engine? What is the efficiency, e, of this engine? (Give your answer as a percent.)

70 cm³ of gasoline are mixed with 70 cm³ of water. What is the average density of the mixture?

The ideal gas in a Carnot engine extracts 1200 J of hoat energy during the isothermal expansion at 250 °C. How much heat energy is exhausted during the isothermal compression at 60°C? Express your answer with the appropriate units.

A heat engine operating between energy reservoirs at 20°C and 590 °C has 32 % of the maximum possible efficiency. How much energy must this engine extract from the hot reservoir to do 900 J of work?

A Carnot heat engine uses a hot reservoirconsisting of a large amount of boiling water and a cold reservoir consisting of a large tub of ice and water. In 5 minutes of operation of the engine, the heat rejected by the engine melts a mass of ice equal to 3.55x10-2 kg.Throughout this problem use Lf = 3.34 x 10^5 J/kg for the heat of fusion forwater. During this time, how much work W is performed by the engine?