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Tue 15 Aug, 2006 06:38 am
why the pressures below both the pistons in a typical pascals law demonstration exp(the hydralic lift one)aren't the same.
bein given that the arrangement is made such tht F/A1=W/A2..whr symbols hav thr usual meanings.????
It would really help if you fixed up your grammar and explain your situation a little bit more, because I have no idea what you're talking about. Well, I do, but I have no idea what it is you can't understand about Pascal's Law.
ans
u must have seen the typical example of pascal's law given in all sorts of undergraduate books.The setup being -2 cylinders of area A1 and A2,connected to each other.Both the cylinders carry a piston on the top them .The space is filled by an incompressible fluid of uniform density.let us assume that in this setup, when we apply a force F on the left cylinder it balances a car of weight W.(pacal's law says F/A1=W/A2).Now my ques. is that ,whether the pressures just below both the pistons are same or not????
The fluid is at rest.
Well, pressure is F/A
F=ma (mass multiplied by the acceleration provided by the gravitational constant).
W=mg, which is pretty much the same thing.
So if F/A = Pressure.
W/A also = pressure.
Therefore F/A1 = W/A2 is the same as saying P1 = P2.
Unless I'm wrong about W=mg being the same thing as F=ma.
Almost, Wolf.
As pressures are inversely proportional to the areas and A1 is NOT equal to A2, therefore P1 is NOT equal to P2.
Remember, P1/A1=P2/A2 (P=pressure and A= area).
In the case you do not apply a pressure to counter a pressure, you can apply a Force to counter a Weight, thus F/A1=W/A2.