1. If heat absorbed by the engine (Q1) = 10,000 Joule, what is the work done by the Carnot engine?
Known:
Low temperature (T2) = 400 K
High temperature (T1) = 800 K
Heat input (Q1) = 10,000 Joule
Wanted: Work done by Carnot engine (W)
Solution:
The efficiency of the Carnot engine :
Work was done by Carnot engine :
W = e Q1
W = (1/2)(10,000) = 5000 Joule
[irp]
2.
Based on graph above, what is the work done by engine in a cycle?
Known :
Low temperature (TL) = 400 K
High temperature (TH) = 600 K
Heat input (Q1) = 600 Joule
Wanted: Work was done by Carnot engine (W)
Solution :
The efficiency of the Carnot engine :
Work done by Carnot engine :
W = e Q1
W = (1/3)(600) = 200 Joule
3. Based on the graph below, what is the efficiency of the Carnot engine?
Known :
Low temperature (TL) = 350 K
High temperature (TH) = 500 K
Wanted : Efficiency of Carnot engine (e)
Solution :
Efficiency of Carnot engine :
e = (TH – TL) / TH
e = (500 – 350) / 500
e = 150 / 500
e = 0.3
e = 30/100 = 30 %
[irp]
4. Based on graph below, the heat engine’s high temperature is 600 K and low temperature is 400 K. If the work done by engine is W, what is the heat output.
Known :
Low temperature (TL) = 400 K
High temperature (TH) = 600 K
Wanted : heat output (Q2)
Solution :
Efficiency of Carnot engine :
e = (TH – TL) / TH
e = (600 – 400) / 600
e = 200 / 600
e = 1/3
Work done by Carnot engine :
W = e Q1
W = work done by engine, e = efficiency, Q1 = heat input
W = (1/3)(Q1)
3W = Q1
Heat output :
Q2 = Q1 – W
Q2 = 3W – W
Q2 = 2W
[irp]
5. Based on graph below, if the heat output is 3000 Joule, what is the heat input.
Known :
Low temperature (TL) = 500 K
High temperature (TH) = 800 K
Heat output (Q2) = 3000 Joule
Wanted : Heat input (Q1)
Solution :
Efficiency of Carnot engine :
e = (TH – TL) / TH
e = (800 – 500) /8600
e = 300 / 800
e = 3/8
Work done by Carnot engine :
W = e Q1
W = (3/8)(Q1)
8W/3 = Q1
Q2 = Q1 – W
Q2 = 8W/3 – 3W/3
Q2 = 5W/3
3Q2 = 5W
W = 3Q2/5 = 3(3000)/5 = 9000/5 = 1800
Heat absorbed by engine :
Q1 = W + Q2 = 1800 + 3000 = 4800 Joule
[irp]
6. An Carnot engine absorbs heat at high temperature 800 Kelvin and efficiency of the Carnot engine is 50%. What is the high temperature to increase efficiency to 80% if the low temperature kept constant.
Known :
If high temperature (TH) = 800 K , efficiency (e) = 50% = 0.5
Wanted : High temperature (TH) if efficiency (e) = 80% = 0.8
Solution :
Low temperature = 400 Kelvin
What is the high temperature (TH) if efficiency (e) = 80 % ?
High temperature = 2000 Kelvin
[irp]
7. A Carnot engine works at high temperature 600 Kelvin with the efficiency of 40%. If the efficiency of the engine is 75% and the low temperature kept constant, what is the high temperature?
Known :
If high temperature (TH) = 600 K , efficiency (e) = 40% = 0.4
Wanted : High temperature (TH) if efficiency (e) = 75% = 0.75
Solution :
High temperature (TH) if efficiency (e) = 75 % ?
High temperature = 1440 Kelvin
