Answer:
Explanation:2.17 m
Given
Mass of man=80 kg
drag coefficient [tex](c_D)=0.5[/tex]
Density of air[tex]=1.35 kg/m^3[/tex]
Required descend velocity(v)=25 m/s
Let d be the diameter of Parachute
In this case Drag force will oppose weight of man so that net force is zero and there is a constant velocity of descend
[tex]W=F_L[/tex]
[tex]F_L=\frac{c_DA\rho v^2}{2}[/tex]
W=mg
[tex]80\times 9.81=\frac{0.5\times \frac{\pi d^2}{4}\times 1.35\times 25^2}{2}[/tex]
[tex]784.8=165.691\times d^2[/tex]
d=2.17 m
