A U-shaped tube open to the air at both ends contains some mercury. A quantity of water is carefully poured into the left arm of the U-shaped tube until the vertical height of the water column is `15.0 cm`.
(a) What is the gauge pressure at the water mercury interface ?
(b) Calculate the vertical distance h from the top of the mercury in the right hand arm of the tube to the top of the water in the left-hand arm.
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Answer

A, C

Explanation

(a) Gauge pressure=`rho_(w)gh_(w)`
`=(10^(3))(9.8)(0.15)`
`=1470 N//m^(2)`
(b) Let us calculate pressure of two sides at the level of water and mercury interface.
`p_(0)+rho_(w)gh_(w)=p_(0)+rho_(Hg)gh_(Hg)`
`:. (1) (15) = (13.6) (15-h)`
`h =13/9 cm`