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BecomeMyFan=D

  • 3 years ago

An engine burns 1.4 kg of gasoline per hour and yields 3.5 kW of power. Calculate the efficiency of the engine when the heating value of gasoline is 43 MJ/kg.

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  1. BecomeMyFan=D
    • 3 years ago
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    i dont even know where to start

  2. BecomeMyFan=D
    • 3 years ago
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    ANY help, even a formula or a rule or a hint, anything will help

  3. BecomeMyFan=D
    • 3 years ago
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    i just know efficiency = input/output

  4. lokisan
    • 3 years ago
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    Yep, calm down.,,

  5. BecomeMyFan=D
    • 3 years ago
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    oh, sorry, it is output/input

  6. BecomeMyFan=D
    • 3 years ago
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    ok,.... i am calm

  7. lokisan
    • 3 years ago
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    The heating value is the amount of heat energy produced by complete combustion in a given quantity. Take a basis of 1 hour. Then your engine burns 1.4kg of gasoline, which yields a maximal amount of thermal energy to use for work as\[43MJ/kg \times 1.4 kg=60.2MJ\]In one hour, your engine produces from this energy, \[\frac{3500J}{s}\times \frac{3600s}{h}=12.6MJ\]The efficiency is the amount of work per unit energy input, which is \[\eta = \frac{12.6MJ}{60.2MJ}=0.209\]to 3 significant figures.

  8. lokisan
    • 3 years ago
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    This is the first time I've used 'heating value' for anything like this, so if the answer's wrong, I couldn't find an appropriate definition.

  9. BecomeMyFan=D
    • 3 years ago
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    so, can i say that efficiancy is 20.9%?

  10. lokisan
    • 3 years ago
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    Yes

  11. BecomeMyFan=D
    • 3 years ago
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    ok, thank you, i already faned you long time ago, so cant fan again :(

  12. lokisan
    • 3 years ago
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    Yeah I know - no worries :)

  13. lokisan
    • 3 years ago
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    The answer makes sense - I've seen values between 10 and 50% for internal combustion engines.

  14. BecomeMyFan=D
    • 3 years ago
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    then it is probably correct, i also know that cobustion engines are very unefficient

  15. BecomeMyFan=D
    • 3 years ago
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    hey anwar

  16. AnwarA
    • 3 years ago
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    hi :)

  17. BecomeMyFan=D
    • 3 years ago
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    want a fan?

  18. AnwarA
    • 3 years ago
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    would you be one if I say yes?

  19. BecomeMyFan=D
    • 3 years ago
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    ...

  20. AnwarA
    • 3 years ago
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    lol

  21. BecomeMyFan=D
    • 3 years ago
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    you got it

  22. AnwarA
    • 3 years ago
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    thanks!!

  23. BecomeMyFan=D
    • 3 years ago
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    anwar, can you please fan lokisan, because he helped me alot and i can only fan him once

  24. AnwarA
    • 3 years ago
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    lol you really care about others :P.. I already did anyways

  25. AnwarA
    • 3 years ago
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    so you faned me just as an exchange for me to fan the guy huh? :(

  26. BecomeMyFan=D
    • 3 years ago
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    nah, would have faned you anyway

  27. sstarica
    • 3 years ago
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    lol andy, you and your fanning job~ ^_^

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