(given atmospheric pressure $P_{A}=1.01 \times 10^{5}\,Pa$, density of water $\rho_{ w }=1000\,kg / m ^{3}$ and gravitational acceleration $g=10\,m / s ^{2}$ )
Assuming there is no atmospheric pressure on piston
$\frac{5 \times 10^{5}}{\pi}+10^{3} \times 10 \times 10=1.01 \times 10^{5}+\frac{1}{2} \times 10^{3} \times v_{e}^{2}$
$v_{e}=17.8\,m / s$

Density of whole blood, $\rho=1.06 \times 10^{3} \;kg m ^{-3}$
