Answer:
362.41 km/h
Explanation:
F = Force
m = Mass = 84 kg
g = Acceleration due to gravity = 9.81 m/s²
C = Drag coefficient = 0.8
ρ = Density of air = 1.21 kg/m³
A = Surface area = 0.04 m²
v = Terminal velocity
F = ma
[tex]F=\frac{1}{2}\rho CAv^2\\\Rightarrow mg=\frac{1}{2}\rho CAv^2\\\Rightarrow v=\sqrt{2\frac{mg}{\rho CA}}\\\Rightarrow v=\sqrt{2\frac{20\times 9.81}{1.21\times 0.8\times 0.04}}\\\Rightarrow v=100.66924\ m/s[/tex]
Converting to km/h
[tex]100.66924\times 3.6=362.41\ km/h[/tex]
The terminal velocity of the stone is 362.41 km/h
Answer:
324.14 km/h
Explanation:
Data:
mass, m = 20 kg
vertical cross-sectional area, A = 0.040 m^2
drag coefficient, C = 0.80
air density, ρ = 1.21 kg/m^3
coefficient of kinetic friction, μ = 0.80
Eq. 6-14:
Drag-Force = (C*ρ*A*v^2)*(1/2) (where v is wind speed)
But Drag-Force is also = m*g*μ (where g is standard gravitational acceleration = 9.81 m/(s^2)). Therefore:
m*g*μ = (C*ρ*A*v^2)*(1/2)
Solving for v
v = √[m*g*μ*2/(C*ρ*A)]
v = √[20*9.81*0.8*2/(0.8*1.21*0.04)]
v = 90.04 m/s
To convert to km/h, multiply by 3.6
v = 90.04*3.6 = 324.14 km/h
