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A simple U tube contains mercury to the same level in both of its arm.If water is poured to a height of 13.6 cm in one arm,how much will be the rise in mercury level in the other arm.Given: density of mercury=13.6 * 1000 kg/m cube & density of water = 1000 kg/m cube.

When water is added to one side of the U tube, the rise in mercury level of the other side of the U tube will be depend on the density of water and mercury.

The height of water added in one arm = 13.6cm, we have to calculate the corresponding rise in level in the other arm

The pressure difference tn the two arms will be equal

So, the pressure difference in water column = the pressure difference in the other arm or mercury

                     i.e. h_Hg d g  = h_W d g

                          h_Hg    = h_W×density of water × g ÷ density of mercury × g

                                  = 13.6cm × 1000kg/m³ × g ÷ 13.6 × 1000kg/m³ × g

                                  = 1cm

i.e. When 13.6cm water is added to one arm of the U tube, only a height of 1cm will be the rise in mercury level in the other arm.