Q57 / 57 · KVPY 2019 (SA) · Physics

A healthy adult of height 1.7 m has an average blood pressure (BP) of 100 mm of Hg. The heart is typically at a height of 1.3 m from the foot. Take, the density of blood to be 103 kg/m3 and note that 100 mm of Hg is equivalent to 13.3kPa (kilo pascals). The ratio of BP in the foot region to that in the head region is close to
 

  • A
    one
     
  • B
    two
  • Correct answer
    C
     three
     
  • D
    four

Solution

Figure

Pressure at head level =pheart -ρgh

=13.3-103×10×0.4

=9.3kPa

Pressure at foot level =pheat +ρgh

=13.3+103×10×1.3

=26.3kPa

So, ratio =26.39.3≈2.9 or 3

Hence, the correct answer is option: 'C'.

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