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mayankdevnani

  • 3 years ago

A steam engine has an efficiency of 20%.It is given an energy of 1000 cal.per minute.What is the actual work done by it in joule and in calories? a) 100 cal,800 J b) 200 cal,873 J c)10 cal,80 J d)100 cal,100 J

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  1. mayankdevnani
    • 3 years ago
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    @amistre64 @ParthKohli @hartnn @Callsito @Zarkon @Hero @.Sam. @estudier @ganeshie8 @ajprincess @Algebraic!

  2. mayankdevnani
    • 3 years ago
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    @Callisto

  3. amistre64
    • 3 years ago
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    im not sure since we havent gone over this in my physics class yet, but i would say that 20% efficiency means that 20% of the 1000 cals are used; giving us 200 cals in the answer at least

  4. SheldonEinstein
    • 3 years ago
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    May I help?

  5. amistre64
    • 3 years ago
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    please do :)

  6. mayankdevnani
    • 3 years ago
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    ofcourse @SheldonEinstein

  7. SheldonEinstein
    • 3 years ago
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    ;) OK so first of all what @amistre64 discussed in his previous comment is very imp. to do this quest., so @mayankdevnani do you know what does efficiency mean?

  8. mayankdevnani
    • 3 years ago
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    ok @amistre64 then

  9. mayankdevnani
    • 3 years ago
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    yaa

  10. mayankdevnani
    • 3 years ago
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    efficiency=winout/winin*100

  11. mayankdevnani
    • 3 years ago
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    right @SheldonEinstein

  12. SheldonEinstein
    • 3 years ago
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    Yeah or in simpler words it is : \(\large{\frac{\textbf{Output}}{\textbf{Input}}\times 100}\) it is 100%...

  13. mayankdevnani
    • 3 years ago
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    yaa

  14. SheldonEinstein
    • 3 years ago
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    So, what we have is output/input * 100% = 20% , correct?

  15. mayankdevnani
    • 3 years ago
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    correct

  16. SheldonEinstein
    • 3 years ago
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    Ok so now, let me understand the second line of the quest. , is the output = 1000 calorie ?

  17. mayankdevnani
    • 3 years ago
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    yaa

  18. mayankdevnani
    • 3 years ago
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    then

  19. mayankdevnani
    • 3 years ago
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    @SheldonEinstein then

  20. SheldonEinstein
    • 3 years ago
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    Oh sorry wait!

  21. mayankdevnani
    • 3 years ago
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    yaa

  22. SheldonEinstein
    • 3 years ago
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    I am getting diff. answer so I am checking it, sorry , it will require some patience.

  23. mayankdevnani
    • 3 years ago
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    ok

  24. SheldonEinstein
    • 3 years ago
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    Quest. is wrong

  25. mayankdevnani
    • 3 years ago
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    why?? no it is right

  26. SheldonEinstein
    • 3 years ago
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    Time is not given.. though if you take 1 minute it is 200 cal.

  27. mayankdevnani
    • 3 years ago
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    yaa

  28. SheldonEinstein
    • 3 years ago
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    See , Power = 1000 cal/minute (given)

  29. SheldonEinstein
    • 3 years ago
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    use this and you will get 200 cal. as answer.

  30. mayankdevnani
    • 3 years ago
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    so what's the work done?

  31. SheldonEinstein
    • 3 years ago
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    W = P * time if T = 1 second , W = P ... that's it , find P(output) .. (using efficiency = Ouput/Input *100%) in Cal. per minute , that will be your answer

  32. SheldonEinstein
    • 3 years ago
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    200 cal.... = WORK DONE

  33. mayankdevnani
    • 3 years ago
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    no

  34. mayankdevnani
    • 3 years ago
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    but the work done is in joule

  35. mayankdevnani
    • 3 years ago
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    @ParthKohli @Preetha

  36. mayankdevnani
    • 3 years ago
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    @SheldonEinstein

  37. mayankdevnani
    • 3 years ago
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    @myininaya

  38. SheldonEinstein
    • 3 years ago
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    Is my answer correct, i.e. 200 cal, 873 J ?

  39. mayankdevnani
    • 3 years ago
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    yaa

  40. SheldonEinstein
    • 3 years ago
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    So where is the problem? ?? ? ?

  41. mayankdevnani
    • 3 years ago
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    873 J how??

  42. mayankdevnani
    • 3 years ago
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    @amriju

  43. mayankdevnani
    • 3 years ago
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    @SheldonEinstein how you got it 873J

  44. SheldonEinstein
    • 3 years ago
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    I got 200 Cal, and it is in options, soo....

  45. mayankdevnani
    • 3 years ago
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    but it's wrong

  46. mayankdevnani
    • 3 years ago
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    i need solution

  47. mayankdevnani
    • 3 years ago
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    can you help me @amriju

  48. SheldonEinstein
    • 3 years ago
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    200 cal * 4.184 = 836 J (approx. ) not equal to 873 Joule , hence I think the options are wrong..

  49. mayankdevnani
    • 3 years ago
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    no it was not wrong

  50. amriju
    • 3 years ago
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    work done is 20 percnt of the energy given...thats efficiency....so per minute is 20percnt of 1000 cal...thats 200 cal...convert to joules

  51. mayankdevnani
    • 3 years ago
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    so 1cal.=? j @amriju

  52. amriju
    • 3 years ago
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    4.2...approx..the correct is 4.187...

  53. mayankdevnani
    • 3 years ago
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    is it 4.37

  54. amriju
    • 3 years ago
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    nope

  55. mayankdevnani
    • 3 years ago
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    why??

  56. amriju
    • 3 years ago
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    thats how it is defined...both are units...and 1 cal is defined as 4.187 joules...

  57. SheldonEinstein
    • 3 years ago
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    That is what I was saying @amriju

  58. mayankdevnani
    • 3 years ago
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    in my solution book...the answer is as follows- \[\frac{20}{100}=\frac{W}{1000}=200 calorie\] OR \[200\times4.37=873J\]

  59. mayankdevnani
    • 3 years ago
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    is that right?? @amriju and @SheldonEinstein

  60. SheldonEinstein
    • 3 years ago
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    That is wrong, 1 Cal. = 4.187 Joule NOT 4.37 joule...

  61. mayankdevnani
    • 3 years ago
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    ok... thnx... @SheldonEinstein and @amriju

  62. amriju
    • 3 years ago
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    u may jst check on wikipedia...and its seems that none of the options are correct...the closest being 200, 837

  63. amistre64
    • 3 years ago
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    just for reference http://www.wolframalpha.com/input/?i=200+calorie+to+joule

  64. amistre64
    • 3 years ago
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    if your options are truely: 200,873 then its most likely a typo and prolly meant to be read as 200,837

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