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## Homework Statement

1. a 100m long copper wire of diameter 4mm is heater from 20C to 80C. What is the change in the length of the wire?

2. a 0.2m diameter aluminium sphere is cooled from 250C to 0C. What is the change in the volume of the sphere?

The coefficients of linear and cubic expansion were given for both materials.

## Homework Equations

α(L) = dL/dT(1/L)

α(V) = dV/dT(1/V)

## The Attempt at a Solution

For the first question is it not just a simple substitution exercise using the formula α(L) = dL/dT(1/L)? The fact that the diameter was provided is confusing me though.

For the second question isn't it just using the second equation α(V) = dV/dT(1/V), where V will be 4/3 * (pi) * r^3 and dT is -250?

Thanks, point out any incorrect observations!

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