Exam 16: Electrical Energy and Capacitance: Part A

A system is acted on by its surroundings in such a way that it receives 50 J of heat while simultaneously doing 70 J of work.What is its net change in internal energy?

The volume of an ideal gas changes from 0.40 to 0.55 m³ although its pressure remains constant at 50,000 Pa.What work is done by the system ON its environment?

A 4-mol ideal gas system undergoes an adiabatic process where it expands and does 28 J of work on its environment.What is its change in internal energy?

A 600-MW electric power plant has an efficiency of 30%.It loses its waste heat in large cooling towers.Approximately how much waste heat (in MJ)is discharged to the atmosphere per second?

A cylinder containing an ideal gas has a volume of 3.0 m³ and a pressure of 1.0 × 10⁵ Pa at a temperature of 300 K.The cylinder is placed against a metal block that is maintained at 900 K and the gas expands as the pressure remains constant until the temperature of the gas reaches 900 K.The change in internal energy of the gas is 9.0 × 10⁵ J.Find the change in entropy of the block associated with the heat transfer to the gas.

A system has an increase in internal energy of 60 J while 90 J was removed from the system by heat.How much work was involved during this process and was it done on the system or done on its environment?

Which of the processes on a monatomic ideal gas given below will result in the temperature of the gas increasing? W is the work done by the gas.

A cylinder containing an ideal gas has a volume of 3.0 m³ and a pressure of 1.0 × 10⁵ Pa at a temperature of 300 K.The cylinder is placed against a metal block that is maintained at 900 K,and the gas expands as the pressure remains constant until the temperature of the gas reaches 900 K.The change in internal energy of the gas is +6.0 × 10⁵ J.How much heat did the gas absorb?

An electrical power plant manages to send 88% of the heat produced in the burning of fossil fuel into the water-to-steam conversion.Of the heat carried by the steam,30% is converted to the mechanical energy of the spinning turbine.Which of the following choices best describes the overall efficiency of the heat-to-work conversion in the plant (as a percentage)?

A heat engine receives 6000 J of heat from its combustion process and loses 3600 J through the exhaust and friction.What is its efficiency?

A 4-mol ideal gas system undergoes an adiabatic process where it expands and does 28 J of work on its environment.How much heat is received by the system?

Two kilograms of water at 1.00 atm at the boiling point of 100°C is heated until all the water vaporizes.What is its change in entropy? (For water,L_v = 2.26 × 10⁶ J/kg)

Consider a Carnot cycle starting at the state of highest pressure and smallest volume.Call the isothermal expansion from this state step 1,the adiabatic expansion which follows step 2,the isothermal compression that then follows step 3,and the adiabatic compression which returns the system to the initial state step 4.In which steps does the internal energy of the system increase?