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Calculate the work against gravity required to build a cylindrical tower?
Calculate the work against gravity required to build a cylindrical tower of height 19 ft and radius 7 ft out of brick. Assume that brick has density 80 lb/ft3. Enter your answer in terms of pi, or as a number accurate to three places after the decimal point.
I got an answer of 6.934 * 10^6 after trying 9.8 * 80 * 7^2 and then integrated from zero to 19...but i got it wrong so apparently i did it wrong...thanks for any help
1 Answer
- BrambleLv 71 decade agoFavorite Answer
The work required = E = weight of tower w x height of its centre of gravity h = w.h
I assume the tower is solid since you give no inner radius. h=19/2 =9.5.
Hence:
E = π x 7² x 80 x 19 x 9.5 = 2.223 x 10^6 ft.lb
