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Question
During blood transfusion the needle is inserted in a vein where the gauge pressure is 2000 Pa. At what height must the blood container be placed so that blood may just enter the vein? [Use the density of whole blood from Table 10.1].
Solution 1
Gauge pressure, P = 2000 Pa
Density of whole blood, ρ = 1.06 × 103 kg m–3
Acceleration due to gravity, g = 9.8 m/s2
Height of the blood container = h
Pressure of the blood container, P = hρg
`:.h = P/(rhog)`
`= 200/(1.06xx10^3xx9.8)`
= 0.1925 m
The blood may enter the vein if the blood container is kept at a height greater than 0.1925 m, i.e., about 0.2 m.
Solution 2
h=P/ρg =200/(1.06 x 103 x 9.8) =0.1925 m
The blood may just enter the vein if the height at which the blood container be kept must be slightly greater than 0.1925 m i.e„ 0.2 m.
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