In 1654 Otto von Guericke, inventor of the air pump, gave a demonstration before
ID: 3087077 • Letter: I
Question
In 1654 Otto von Guericke, inventor of the air pump, gave a demonstration before the noblemen of the Holy Roman Empire in which two teams of eight horses could not pull apart two evacuated brass hemispheres. Assume that the hemispheres have thin walls, so that R in the figure may be considered both the inside and outside radius. Taking R as 42 cm, the inside pressure as 0.12 atm, and the outside pressure as 1.0 atm, find the force magnitude the teams of horses would have had to exert to pull apart the hemispheres.
Explanation / Answer
net force acting on the both the hemisphere = P*A
where P= 1-0.12 = 0.88 atm = 0.88*1.01325*10^5 Pascal
Area= (pi)*R^2 = 3.14*(0.42)^2 square meter
from here calculate the net force and divide it by 746 to convert it in hp