# Calculating how massive a object may be when supported by a suction cup mounted to a

1. Oct 4, 2012

### savva

1. The problem statement, all variables and given/known data
How massive an object can be supported by a 5.6 -diameter suction cup mounted on a vertical wall, if the coefficient of friction between cup and wall is 0.65? Assume normal atmospheric pressure.

2. Relevant equations
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3. The attempt at a solution
I calculated the maximum force which I realised was when the pressure inside the suction =0
Therefore Fmax=pA=101.3*10^3(pi(0.028^2))= 250N.

I don't know how to find the how much mass can be supported by the suction cup. I tried a number of answers and they were all wrong.

2. Oct 5, 2012

### voko

Re: Calculating how massive a object may be when supported by a suction cup mounted t

If you hook up some mass m to the cup, what forces will be acting on the cup?

3. Oct 5, 2012

### rude man

Re: Calculating how massive a object may be when supported by a suction cup mounted t

Turn the experiment 90 degrees in your mind so that the suction cup is resting horizontally atop the wall instead of vertically against it.