Problems worked on in class by teams of students.
Re: Section 8.5
1. (Similar to problem 17)
A gas station stores its gasoline in a tank under the ground. The tank is a cylinder lying
horizontally on its side. (In other words, the tank is NOT standing vertically on one of its flat
ends.) A 1060 gallon fuel tank has a diameter of 48 inches and a length of 144 inches. (*)
a. If its top is 10 ft under the ground, find the total amount of work needed to pump all the
gasoline out of the tank. (Gasoline weighs 42 lbs/cubic feet).
b. If the tank was buried vertically instead, what would the force of the gasoline on the circular
end be?
Ref for the dimensions of different fuel tanks:
(*) http://hansontank.us/airtanks.html?gclid=CMfpkt3x_pUCFQNfFQodwCYEEA
2. (Similar to problem 19)
Sometimes triangular troughs are used to drain water, skim fluid from tanks etc. Suppose we
have a triangular trough: the cross-section is a triangle with all sides 8 inches long and we will
assume it has a length of 10 ft.
a. Find the force of the water on the triangular end.
b. Find the work to pump all the water over the top.
Ref. For examples of the use of triangular troughs, see for instance:
* Patent on an oiltank skimming device http://www.freepatentsonline.com/3786826.html
* Drainage in Areas Other than Airfields (report by Army corps of engineers)
http://www.wbdg.org/ccb/DOD/UFC/ufc_3_230_17fa.pdf
3. (Similar to problem 25)
Rescue and salvage effort when ships sink are heavily influenced by the depth at which the
wrecked ship is found.
The Atocha is a famous shipwreck from the 17th century. The Atcoha sank off the Florida coast
in 1622. The ship was laden with treasures. The Atocha was found at a depth of 17 meters (55.8
feet). Archaeologists were able to dive at this depth.
a. Find the water pressure in pounds per square foot.
b. In photographs divers / researchers are seen holding clipboards. Assume these clipboards are 1
foot square. What is the force on the clipboard when held horizontally? Vertically?
c. The ships went down with everything on board, including cups, saucers and plates. What
would the total force be on a round plate of diameter .5 ft if it had landed on the bottom of the
ocean in a vertical position?
