Calculate the linear expansivity of a material of length 120m that assumes a new length of 12.05m when heated through a temperature of 90°C

Surely you mean the length was 12.0m. If so, then

12.05 = 12.0(1 + 90α)
1 + 90α = 1.004167
α = 0.004167/90 = 0.0000463

To calculate the linear expansivity of a material, we can use the formula:

Linear expansivity (α) = (final length - initial length) / (initial length * change in temperature)

Given:
Initial length (L1) = 120m
Final length (L2) = 12.05m
Change in temperature (ΔT) = 90°C

Using the formula, we can substitute these values to calculate the linear expansivity:

α = (L2 - L1) / (L1 * ΔT)
α = (12.05m - 120m) / (120m * 90°C)

First, let's convert the length from meters to centimeters so the units match:

L1 = 120m = 12000cm
L2 = 12.05m = 1205cm

Now we can substitute the values into the formula:

α = (1205cm - 12000cm) / (12000cm * 90°C)
α = -9780cm / 1080000cm * °C

Simplifying:

α ≈ -0.009°C^(-1)

Therefore, the linear expansivity of the material is approximately -0.009°C^(-1).