rasen58 Posted March 2, 2015 Share Posted March 2, 2015 (edited) A flask is closed tightly with a rubber stopper 3.00 cm in diameter. All the air in the flask is then removed. How much force is necessary to remove the stopper from the evacuated flask? (1 atm = 1.013 x 10^5 N/m^2) I have no idea how to do this problem. I think I'm supposed to use Bernoulli's equation, but I'm not sure how exactly to use it. I also tried using P = F/A So F = P*A = 1 x 10^5 x pi x (0.03)^2 = 283 But the answer is 71.6 N. Edited March 2, 2015 by rasen58 Link to comment Share on other sites More sharing options...
studiot Posted March 2, 2015 Share Posted March 2, 2015 But the answer is 71.6 N. Well it would be. Look very carefully at your calculation for the area of the stopper. Link to comment Share on other sites More sharing options...
rasen58 Posted March 3, 2015 Author Share Posted March 3, 2015 Oh wow, I used the diameter instead of the radius. Thanks. Link to comment Share on other sites More sharing options...
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