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, 201510 yr by rasen58

 

But the answer is 71.6 N.

 

 

 

Well it would be.

 

Look very carefully at your calculation for the area of the stopper.

 

Oh wow, I used the diameter instead of the radius. Thanks.