1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: 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
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted