In the past decades, coal was used to heat the engine of a steam locomotive. With the engine, a steam locomotive can be accelerated to a desired speed. Calculate the efficiency of the steam engine, when the calorific value of coal is H = 27.9000 , velocity of the m、 = 115 t weighted locomotive is v = 93 km. Amount of coal used is mc = 11 kg MJ kg h What is the amount of heat? MJ Q = What is the kinetic energy? Ek MJ = What is the efficiency? η =

In the past decades, coal was used to heat the engine of a steam locomotive. With the engine, a steam locomotive can be accelerated to a desired speed. Calculate the efficiency of the steam engine, when the calorific value of coal is H = 27.9000 , velocity of the m、 = 115 t weighted locomotive is v = 93 km. Amount of coal used is mc = 11 kg MJ kg h What is the amount of heat? MJ Q = What is the kinetic energy? Ek MJ = What is the efficiency? η =

Principles of Physics: A Calculus-Based Text

5th Edition

ISBN:9781133104261

Author:Raymond A. Serway, John W. Jewett

Publisher:Raymond A. Serway, John W. Jewett

Chapter18: Heat Engines, Entropy, And The Second Law Of Thermodynamics

Section: Chapter Questions

Problem 7P

See similar textbooks

Similar questions

A heat pump has a coefficient of performance of 3.80 and operates with a power consumption of 7.03 103 W. (a) How much energy does it deliver into a home during 8.00 h of continuous operation? (b) How much energy does it extract from the outside air?
An ideal gas expands isothermally along AB and does 700 J of work (see below). (a) How much heat does the gas exchange along AB? (b) The gas then expands adiabatically along BC and does 400 J of work. When the gas returns to A along CA, it exhausts 100 J of heat to its surroundings. How much work is done on the gas along this path?
The energy output of a heat pump is greater than the energy used to operate the pump. Why doesn't this statement violate the first law of thermodynamics?
Consider a transformation from point A to B in a two-step process. First, the pressure is lowered from 3 MPa at point A to a pressure of 1 MPa, while keeping the volume at 2 L by cooling the system. The state reached is labeled C. Then the system is heated at a constant pressure to reach a volume of 6 L in the state B. (a) Find the amount of work on the ACB path. (b) Find the amount of heat exchanged by the system when it goes from A to B on the ACB path. (c) the change in the internal energy when the AB process occurs adiabatically with the AB change though the two-step process on the ACB path.
(a) What is the best coefficient of performance for a refrigerator that cools an environment at 30.0C and has heat transfer to another environment at 45.0C ? (b) How much work in joules must be done for a heat transfer of 4186 kJ from the cold environment? (c) What is the cost of doing this if the work costs 10.0 cents per 3.60106J (a kilowatthour)? (d) How many kJ of heat transfer occurs into the warm environment? (e) Discuss what type of refrigerator might operate between these temperatures.
(a) On a winter day, a certain house loses 5.00108J of heat to the outside (about 500,000 Btu). What is the total change in entropy due to this heat transfer alone, assuming an average indoor temperature of 21.0C and an average outdoor temperature of 5.00C ? (b) This large change in entropy implies a large amount of energy has become unavailable to do work. Where do we find more energy when such energy is lost to us?
In performing 100.0 J of work, an engine discharges 50.0 J of heat. What is the efficiency of the engine?
Consider the processes shown below. In the processes AB and BC, 3600 J and 2400 J of heat are added to the system, respectively. (a) Find the work done in each of the processes AB, BC, AD, and DC. (b) Find the internal energy change in processes AB and BC. (c) Find the internal energy difference between states C and A. (d) Find the total heat added in the ADC process. (e) From the information give, can you find the heat added in process AD? Why or why not?
A Carnot engine performs 100 J of work while discharging 200 J of heat each cycle. After temperature of the hot reservoir only is adjusted, it is found that the engine now does 130 J of work while discarding the same quantity of heat. (a) What are the initial and final efficiencies of the engine? (b) What is the fractional change in the temperature of the hot reservoir?
Suppose an ideal (Carnot) heat pump could be constructed for use as an air conditioner. (a) Obtain an expression for the coefficient of performance (COP) for such an air conditioner in terms of Tb and Tc. (b) Would such an air conditioner operate on a smaller energy input if the difference in the operating temperatures were greater or smaller? (c) Compute the COP for such an air conditioner if the indoor temperature is 20.0C and the outdoor temperature is 40.0C.
Steam locomotives have an efficiency of 17.0% and operate with a hot steam temperature of 425C. (a) What would the cold reservoir temperature be if this were a Carnot engine? (b) What would the maximum eficiency of this steam engine be if its cold reservoir temperature were 150C ?
A thermal engine produces 4 MJ of electrical energy while operating between two thermal baths of different temperatures. The working substance of the engine discharges 5 MJ of heat to the cold temperature bath. What is the efficiency of the engine?