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In question 3-37,we have P-p(ATM)=density * g* h and we get h as 8.3 m But the answer is 1.53 m.How and why?What is wrong in my approach?

  • 2
    $\begingroup$ What value did you use for the density of mecury? $\endgroup$
    – Solar Mike
    Mar 9, 2018 at 7:01
  • $\begingroup$ The thought that a doctor's office would put on a BP cuff and then dump my vein into that apparatus is frightening, to say the least! $\endgroup$ Mar 9, 2018 at 16:14
  • $\begingroup$ @CarlWitthoft only have to go back a couple of hundred years and blood-letting was a « current » treatment... $\endgroup$
    – Solar Mike
    Mar 9, 2018 at 16:25
  • $\begingroup$ @SolarMike in your childhood, then? $\endgroup$ Mar 9, 2018 at 18:46
  • $\begingroup$ I have taken it as 13600 kg/m^3 $\endgroup$
    – Shwetha
    Mar 23, 2018 at 4:02

1 Answer 1


Pressure due to mercury is: Pm = 13600*9.81*0.12 = 16010

So, that is the pressure created by the blood and it will then rise:

hb = 16010/(1040*9.81) = 1.57m

Obviously, I have used constants I am aware of - subtle differences will give 1.53m...

Edit the density of mercury is 13560kg/m3 so that is where my error comes in...

  • $\begingroup$ Then please accept the answer by using the “tick” .... $\endgroup$
    – Solar Mike
    Mar 23, 2018 at 5:17

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