Giraffes are a wonder of cardiovascular engineering. Calculate the difference in pressure (in atmospheres) that the blood vessels in a giraffe’s head must accommodate as the head is lowered from a full upright position to ground level for a drink. The height of an average giraffe is about 6 m.

Whenever a fluid flows through a specific cross-section, it means there would be a pressure difference. The direction of flow of any fluid decides with the help of pressure difference. The relation between the flow rate of fluid and pressure difference is a linear one.

The height of the average giraffe is \(h = 6\;{\rm{m}}\).

The expression of the pressure difference in the blood produced due to elevation change is given by,

\(\Delta P = \rho gh\).

Here, \(\rho \) is the density of blood \(\left( {\rho = 1.05 \times {{10}^3}\;{\rm{kg/}}{{\rm{m}}^{\rm{3}}}} \right)\), \(g\) is the gravitational acceleration \(\left( {g = 9.81\;{\rm{m/}}{{\rm{s}}^{\rm{2}}}} \right)\) and \(\Delta P\) is the pressure difference.

Substitute all the known values in the above expression.

\(\begin{array}{c}\Delta P = \left( {1.05 \times {{10}^3}\;{\rm{kg/}}{{\rm{m}}^{\rm{3}}}} \right)\left( {9.81\;{\rm{m/}}{{\rm{s}}^{\rm{2}}}} \right)\left( {6\;{\rm{m}}} \right)\\ = \left( {61803\;{\rm{Pa}}\; \times \frac{{1\;{\rm{atm}}}}{{1.01325 \times {{10}^5}\;{\rm{Pa}}}}} \right)\\ \approx 0.61\;{\rm{atm}}\end{array}\)

Thus, the Pressure difference in the blood vessel is \(0.61\;{\rm{atm}}\).