Heat needed to expand a circular metal plate

[songoku]

Homework Statement

A circular metal plate of diameter D needs Q Joule of heat to expand and the temperature changes from 40^oC to 58^oC. What is the thermal energy needed to expand identical metal plate having twice the diameter for same increase in temperature?

Homework Equations

Q = mcΔT

The Attempt at a Solution

ΔT and c will be constant, but I am not sure about the mass. Should I assume the shape of the circular metal plate is cylinder and the height is constant during heating? So twice diameter means the area becomes 4 times and volume becomes 4 times? Then assuming density is constant, the answer is 4Q?

Thanks

 

[BvU]

Should I assume

Yes, that's all you are given.

 

[songoku]

Thank you very much