Aconcrete bridge is built of 315-cm-long concrete slabs with an expansion joint between them. the slabs just touch on a 115∘f day, the hottest day for which the bridge is designed.

Missing question:
"What is the gap between the slabs when the temperature is 0∘F?"

Solution)

The linear expansion of a solid material that undergoes a temperature change of  is given by

where  is the coefficient of linear expansion of the material, L the length and  the linear expansion.

For concrete, . We also have the length of the slab, .
To find the temperature variation, we must convert first the temperatures in Kelvin:



Therefore, we can find the linear expansion:

This is the variation in length between the two temperatures T=115 F and T=0 F. Therefore, since the slabs just touch at 115 F, their distance is 0, while at T=0 F their gap will be exactly 2.4 mm.

The best description is: . nobody has any idea what q is.