Correct Answer to Question 5 Correct Answer to Question 5
When the water levels are the same on both sides of the manometer, the
pressure of the gas in the bulb is one atmosphere.
When the levels
change to those shown in the diagram, the pressure of the gas in the
bulb is one atmosphere plus the pressure due to a column of water 4 cm
high (the pressure at level L is the same on both sides). So the change
in pressure 
P of the gas is just the pressure
due to h = 4 cm = 0.04 m of water.
The pressure due to a column of
liquid is
P =
gh, where
is the density and g is the gravitational
acceleration. The acceleration g = 9.8 m/sec2 and, for
water, = 1000 Kg/m3.
Hence,
P =
gh = (1000)(9.8)(0.04) =
392 N/m2.
Formula Sheet
Question 5 ...
Question 6 ...
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