Example 5

EXAMPLE 5 What About Burj Khalifa?

Burj Khalifa in Dubai (see Figure 18.6), completed in 2010, is still the world’s tallest skyscraper at 2684 ft (how much is that in meters?), not counting radio and television antennas (see Spotlight 18.1). What is the pressure at the bottom of its walls?

Figure 18.6: Figure 18.6 Actor Tom Cruise dangling from Burj Khalifa in the film Mission Impossible—Ghost Protocol (2012).

The building is made of reinforced concrete, which weighs . Although the building tapers toward the top, we are not far off if we model it as straight up and down—that is, as a rectangular solid. Consider one of its supporting walls. The volume of the wall is its height times the area of its base, or . The weight of the wall is . The pressure at the bottom from the wall’s weight is

where we have rounded off the calculated answer to agree with the degree of precision of the ingredient numbers.

That’s not counting the contents of the tower, which also must be supported.