# Heat needed to expand a circular metal plate

#### songoku

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

2. Homework Equations
Q = mcΔT

3. 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

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#### songoku

Thank you very much

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