A)In 1656, the Burgmeister (mayor) of the town of Magdeburg, Germany, Otto Von G

Question

A)In 1656, the Burgmeister (mayor) of the town of Magdeburg, Germany, Otto Von Guericke, carried out a dramatic demonstration of the effect resulting from evacuating air from a container. It is the basis for this problem. Two steel hemispheres of radius 0.350 m (1.15 feet) with a rubber seal in between are placed together and air pumped out so that the pressure inside is 11.00 millibar. The atmospheric pressure outside is 950 millibar. Calculate the force required to pull the two hemispheres apart.

B)Two equal teams of horses, are attached to the hemispheres to pull it apart. If each horse can pull with a force of 1330N (i.e., about 299 lbs), what is the minimum number of horses required?

Explanation / Answer

Pressure Difference = (950-11) = 939 millibar

939 millibar = 93900N/m^2 = 93900Pa (1 millibar =100N/m2)

P = F/A

93900 = F/ (pi*r^2)

F = 93900*pi*(0.35)^2

F = 36137N

b) no. of horses required to pull the hemisphere = 361367/1330 = 27

so 27 horses are required to pull the hemisphere

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