When heated to 1000°F, how much does a 100ft long length of steel elongate?

When steel is heated, it expands due to thermal expansion, which is a property of materials that leads to an increase in size with an increase in temperature. The formula used to calculate the elongation of steel is based on the coefficient of linear expansion, which for steel is approximately 0.00000651 per degree Fahrenheit.

In this scenario, we first determine the temperature change by considering the difference between the initial and final temperatures, which in this case can be assumed as room temperature (around 70°F) to 1000°F. This results in a temperature increase of approximately 930°F.

Using the formula for linear expansion:

[ \text{Elongation} = \text{Original Length} \times \text{Coefficient of Linear Expansion} \times \text{Temperature Change} ]

Substituting the values:

[ \text{Elongation} = 100 , \text{ft} \times 12 , \text{in/ft} \times 0.00000651 , \text{in/in°F} \times 930°F ]

This calculates to approximately 7.5 inches of elongation. Therefore, while option C states an elongation of 9.