6 ... A
9 ... A
10 ... ok
12 ... A
23 ... ok
24 ... A
a. What is the efficiency of the light bulb? Give your answer as a percentage.
b. What do you think happens to the “lost” energy?
19. The work output is 300 joules for a machine that is 50% efficient. What is the work input?
20. A machine is 75% efficient. If 200 joules of work are put into the machine, how much work output does it produce?
It is Reverse or Reverse fault in other words - I just took the test this was the answer.
Answer:
100°C
Explanation:
The heat gained by the ice equals the heat lost by the steam, so the total heat transfer equals 0.
Heat lost by the steam as it cools to 100°C:
q = mCΔT
q = (3 kg) (2.00 kJ/kg/K) (100°C − 120°C)
q = -120 kJ
Total heat so far is negative.
Heat lost by the steam as it condenses:
q = -mL
q = -(3 kg) (2256 kJ/kg)
q = -6768 kJ
Heat absorbed by the ice as it warms to 0°C:
q = mCΔT
q = (6 kg) (2.11 kJ/kg/K) (0°C − (-40°C))
q = 506.4 kJ
Heat absorbed by the ice as it melts:
q = mL
q = (6 kg) (335 kJ/kg)
q = 2010 kJ
Heat absorbed by the water as it warms to 100°C:
q = mCΔT
q = (6 kg) (4.18 kJ/kg/K) (100°C − 0°C)
q = 2508 kJ
The total heat absorbed by the ice by heating it to 100°C is 5024.4 kJ.
If the steam is fully condensed, it loses a total of -6888 kJ.
Therefore, the steam does not fully condense. The equilibrium temperature is therefore 100°C
B. Mercury, Jupiter, Saturn, and Mars.
C. Mercury, Venus, Jupiter, and Mars.
D. Mercury, Venus, Earth, and Mars
b. remains the same
c. increases