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.

Answer: it will take   4.36 seconds to reach her average velocity 10.69 miles/hour.explanation:   we have equation of motion ,where s is the displacement, a is the acceleration, u is the initial velocity and t is the time taken.average velocity = displacement/ time taken.average velocity = 10.69 miles/hr = 10.69*1.6*1000/(60*60) = 4.75 m/s4.75 = s/ts = 4. 1we also have acceleration = 2.18 m/s², initial velocity = 0 m/sso it will take   4.36 seconds to reach her average velocity 10.69 miles/hour.