# I need help with this MCQ question pleae

1. Aug 10, 2015

### Shiv Narayanan

< Mentor Note -- Poster has been warned to show their work in future schoolwork threads >

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. Aug 10, 2015

### Qwertywerty

Hint : What is formula for ΔQ ? What is power provided ?

3. Aug 10, 2015

### Shiv Narayanan

Hello, Thanks for replying!

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4. Aug 10, 2015

### Qwertywerty

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 .

5. Aug 10, 2015

### Shiv Narayanan

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?

6. Aug 10, 2015

### Qwertywerty

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