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I need help with this MCQ question pleae

  1. Aug 10, 2015 #1
    < Mentor Note -- Poster has been warned to show their work in future schoolwork threads >

    Screenshot 2015-08-10 23.35.26.png Hello! I need help with this question. The answer is D but I don't understand why :/ Thanks!
     
    Last edited by a moderator: Aug 10, 2015
  2. jcsd
  3. Aug 10, 2015 #2
    Please post your attempt .

    Hint : What is formula for ΔQ ? What is power provided ?
     
  4. Aug 10, 2015 #3
    IMG_20150811_001821.jpg Hello, Thanks for replying!
     

    Attached Files:

  5. Aug 10, 2015 #4
    Why is Q1 = Q2 ?

    Heaters are identical , and so power provided by them will be the same . The heat absorbed by the objects in some time ' t ' will depend on their own properties . It will not necessarily be the same for both .
    Try again .

    Hope this helps .
     
  6. Aug 10, 2015 #5
    Oh Yes.. I read the question wrongly. I thought amount of energy provided is the same.

    So, if I am not wrong, the gradient of the graph is the specific heat capacity and since mass of N is 2 times the mass of M, in this case, I can just take the mass of N to be 2kg while the mass of M to be 1kg right? (For me to be able to calculate)

    I find the gradient of N and divide it by 2 as heat capacity is per kg.Then I have to compare with the gradient of M and derive the ratio.. Am I right?
     
  7. Aug 10, 2015 #6
    ΔQ = m*c*ΔT ,
    ∴ P = ΔQ / ΔT = ?

    No , I think it looks more like ( ΔT / Δt ) .
    And no , you can't assume the masses as so . Use P1 / P2 ratio .
     
    Last edited: Aug 10, 2015
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