Anonymous
Anonymous asked in Science & MathematicsPhysics · 10 years ago

# who can answer this physics problem? (Boyle's Law)?

here we go:

the height of mercury column in a barometric tube is 75 cm, The tube has a uniform cross sectional area of 1 cm^2. if the space confined over the mercury surface is 9 cm long, what is the volume of air under the atmospheric pressure that when inserted in the space over the mercury surface in the tube causes a depression in the mercury column to a height of 59 cm? (The temperature is constant)

Relevance

Boyles law can be stated as

PV = const, or P1V1 = P2V2

where P and V are pressure and volume respectively and subscript 1 refers to air under atmospheric conditions, and 2 refers to the same sample of air in the barometer tube.

It goes against the grain somewhat, but I am going to use some very non-SI units of P and V for the sake of convenience in the case of this particular question.

P1 = atmospheric pressure = 75 cmHg

P2 = final pressure = 75 - 59 = 16 cmHg

V2 = 16 + 9 = 25cm^3

V1 = P2*V2/P1 = 16*25/75 = 5.33 cc

To be strictly accurate, the saturated vapour pressure of mercury vapour at the temperatue of the experiment must be added to the value of P1 that I have used.