The apparatus shown in the diagram below is used to measure the density of oil The density of water is 1000 kg m-3 and the atmospheric pressure is 100 000 N m-3.
(a) Calculate the pressure at the liquid surface A inside the tube in N m-2.
(b) Hence, find the pressure at the liquid surface C inside the tube.
(c) Determine the density of oil
[Take g = 10 N/kg where necessary]
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Answer:
(a) Pressure at A = 100 000 + 0.08 Χ 1000 Χ 10 (atm + ρgh)
= 100 800 N m-2
(b) *Star Question*
Pressure at C = Pressure at A (air pressure evens itself throughout in an enclosed space)
= 100 800N m-2
(c)
Atm pressure + pressure due to oil column = 100 800
Pressure due to oil column = 800
0.12 Χ density of oil Χ 10 (ρgh) = 800
Density of oil = 667 kg / m-3
