- #1
baubletop
- 28
- 0
Homework Statement
In a simple model of the wind speed associated with hurricane Emily, we assume there is calm eye 18.8 km in radius. The winds, which extend to a height of 4000 m, begin with a speed of 303.0 km/hr at the eye wall and decrease linearly with radial distance down to 0 km/hr at a distance of 128.8 km from the center. Assume the average density of the air from sea level to an altitude of 4000 m is 0.969 kg/m3. Calculate the total kinetic energy of the winds.
Homework Equations
K = 1/2 mv2
dK = 1/2 dmv2
dA = 2πr dr
The Attempt at a Solution
I tried finding the integral of dK in order to find the total KE.
This gives:
∫dK = ∫1/2 v2ρ*h*2π*r dr
Since v is a function of r, I converted the radii and velocities to meters and found a linear fit that represented v(r), which was:
v = -2.76r + 355137
And since ρ, h, and 2π are constants, they can be taken out of the integral, which gives:
KE = ρhπ ∫[v(r)]2 r dr
Since v(r) is already restricted from the outside of the eye to the outside of the entire hurricane, as far as I know it doesn't need to be further restricted in the integral.
I keep getting wrong answers from this, though, so I'm not quite sure what I'm doing wrong.