Author Question: What is the essential reason that all perpetual motion machines fail? a. Perpetual motion machines ... (Read 50 times)

ashley

  • Hero Member
  • *****
  • Posts: 584
What is the essential reason that all perpetual motion machines fail?
 a. Perpetual motion machines must create energy in order to do useful work, and energy cannot be created.
  b. Perpetual motion machines must at least preserve all the energy in a system, and some is always lost.
  c. Perpetual motion machines run on gasoline, and gasoline is not a renewable resource.
  d. A perpetual motion machine necessarily removes heat from a single-temperature environment.
  e. Perpetual motion machines have to contend with friction, which destroys energy.

Question 2

A refrigerator uses mechanical work to transfer heat from a colder region to a hotter one, as shown in this schematic. Why is it not possible to remove heat from the cold region and transfer it to the hot region without the input of work by an external source?
 a. It would violate the first law of thermodynamics.
  b. It would violate the second law of thermodynamics.
  c. Both a. and b.
  d. It would be possible only if the machine did not lose some energy as heat because of friction.



Li Jun

  • Sr. Member
  • ****
  • Posts: 335
Answer to Question 1

b

Answer to Question 2

b



Related Topics

Need homework help now?

Ask unlimited questions for free

Ask a Question
 

Did you know?

The first documented use of surgical anesthesia in the United States was in Connecticut in 1844.

Did you know?

A good example of polar molecules can be understood when trying to make a cake. If water and oil are required, they will not mix together. If you put them into a measuring cup, the oil will rise to the top while the water remains on the bottom.

Did you know?

Inotropic therapy does not have a role in the treatment of most heart failure patients. These drugs can make patients feel and function better but usually do not lengthen the predicted length of their lives.

Did you know?

More than 4.4billion prescriptions were dispensed within the United States in 2016.

Did you know?

Vaccines cause herd immunity. If the majority of people in a community have been vaccinated against a disease, an unvaccinated person is less likely to get the disease since others are less likely to become sick from it and spread the disease.

For a complete list of videos, visit our video library