Question

SECTION I 01. (D) The Eiffel Tower (Fig. 13-31) is built of wrought iron approximately 300 m tall. Estimate how much its height changes between January (average temperature of 2°C) and July (average temperature of 25 C). Ignore the angles of the iron beams and treat the tower as a vertical beam. Ignore effects of Gravity. (T) A concrete highway is built of slabs 12 m long (15°C). How wide should the expansion cracks between the slabs be (at 15°C) to prevent buckling if the range of temperature is from -15 C to 50°C. 02. (II) A sealed test tube traps 25.0 cm of air at a pressure of 1.00 atm and temperature of 18 °C. The test tube's stopper has a diameter of 1.50 cm and will "pop off the test tube if a net upward force of 10.0 N is applied to it. To what temperature would you have to heat the trapped air in order to "pop off" the stopper? Assume the air surrounding the test tube is always at a pressure of 1.00 atm. NB: Pressure Force/Area

Answer 1

1)Thermal expansion=alpha(L)(delta T)

alpha:coeff of thermal expansion

L=initial length

delta T=change in temperature

Let us say the Eiffel has length L at 20 degree celsius

Then at 2 degree

length decreases by alpha(L)(18)

At 25 degree

length increases by alpha(L)(5)

2)

1)Thermal expansion=alpha(L)(delta T)

alpha:coeff of thermal expansion

L=initial length

delta T=change in temperature

Initial length:12m at 15 degree

maximum expansion=12*alpha*35

The above spacing needs to be provided to prevent buckling.