During each cycle, a heat engine takes in 4.0 J of heat, does 1.0 ...

[ENagel]

During each cycle, a heat engine takes in 4.0 J of heat, does 1.0 J of work, and expels 3.0 J of heat. What is its efficiency?
 
  What will be an ideal response?

Question 2

A blacksmith is flattening a steel plate having dimensions 10 cm  15 cm  1 mm. He has heated the plate to 900 K. If the emissivity of the plate is 0.75,
 
  at what rate does it lose energy by radiation? Ignore any heat exchange with the surroundings. ( = 5.67  10-8 W/m2  K4 )
  A) 360 W
  B) 760 W
  C) 790 W
  D) 850 W
  E) 880 W

[cdmart10]

Answer to Question 1

25

Answer to Question 2

D