# Does the Eiffel Tower become taller during the summer months?

Thermal Expansion is a (property?) of all materials wherein some voodoo magic happens that makes the material expand / contract when subject to heat or cold. I’m an engineer, not a physicist.

In our case, we can figure out the thermal expansion of the Eiffel Tower for a given range of temperature change just by looking up a few things on the interwebs.

First, we need a fancy formula like this:

Then, we need to figure out all the necessary information on the variables. Ultimately, we want to find that “change in length” value so we just need to know a few things:

• Coefficient of Thermal Linear Expansion – Different materials expand and contract differently so we need to determine the construction material. This building is made almost entirely of wrought iron[1]Wrought Iron is basically steel but without all the sweet sweet benefits a bit of carbon adds to the mixture. For reference, wrought Iron is generally something like 25%-50% weaker than most commonly used “building steel” grades. But anyways – since we know the material, we know that α = 6.5 x 10^(-6)[2]using degrees F (that’s right Fahrenheit – I’m no commie!).
• Original Length – In this case – the height of the structure. According to something that looks official[3], the height is 984 feet.

• Temperature Change – I’m going to take the liberty of assuming the OP is looking for the height change from hottest recorded temperature ever to the coldest recorded temperature ever – because I can. So, in our case, for Paris, France, that is 105 degrees F and -11 degrees F[4]. Side note – I’m assuming that the paint prevents the iron from getting really extra hot in the sunlight to simplify my research – but it very well could.

So, when we put the numbers together, we get:

δL = 984′ * 0.0000065 * (105 – (-11)) = 0.75′ = 9 inches! …or 23cm for you metric types.

Of course, this is an over-simplification – but generally speaking, the Eiffel Tower should be a handful of inches taller in the summer than it is in the winter.

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