A glass bottle of soda is sealed with a screw cap. The absolute pressure of the carbon dioxide inside the bottle is 1.80 x10^5pa. Assuming that the top and bottom surfaces of the cap each have an area of .0004M^2, obtain the magnitude of the force that the screw thread exerts on the cap in order to keep it on the bottle. The air pressure outside the bottle is one atmosphere.

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physics - drwls, Sunday, April 8, 2007 at 6:48am
(Area)*(Poutside - Pinside) = Force
Pinside = 1.80*10^5 N/m^2
Poutside = 1 atm = 1.013*10^5 N/m^2
Area = 4*10^-4 m^2
Solve for Force, F

Physics please check - CJ, Sunday, April 8, 2007 at 11:12pm
F = (4.0^-4m^2)(1.013*10^5 N/m^2 - 1.80*10^5 N/m^2)

F = (0.0004)(-78799)

F = -31.5196

Correct procedure, I didn't check calc math. Units?

Answer 1

F= +31.5196

total forces = 0
PA(Co)-PA(atm)-F(thread)=0
F=PA(CO)-PA(atm)