RChung wrote:
Ale Martinez wrote:
Robert, the model I used for regresion is based on end-to-end conservation of energy (deltaPE+deltaKE = workAeroDrag + workRRdrag), so:
[M*g*h + 1/2*M*(Vi^2-Vf^2)] = [1/2*rho*sum(Vi^3)] * CdA + [M*g*sum(Vi)] * Crr
where Vi=initial velocity, Vf=final velocitiy, Vi=velocity at i second from start, h=descent from start to finish.
BTW, Ale, the first Vi is different from the second Vi?
Sorry for the confussion, Vi stands for Vinitial in the left side of the equation but for V at i second from start inside the sums...
RChung wrote:
That is, if you count the velocities as V0, V1, V2, ..., Vfinal then the model to estimate is [M*g*h + 1/2*M*(V0^2-Vfinal^2)] = [1/2*rho*sum(Vi^3)] * CdA + [M*g*sum(Vi)] * Crr
where i = 1, 2, 3, ..., final
Exactly, that was the idea, then I divide all terms by [M*g*sum(Vi)] to use linear regresion with slope CdA and intercept Crr in the spreadsheet:
{ [1/2*rho*sum(Vi^3)] / [M*g*sum(Vi)] } * CdA + Crr = [M*g*h + 1/2*M*(V0^2-Vfinal^2)] / [M*g*sum(Vi)]
where i = 1, 2, 3, ..., final
Ale Martinez
www.amtriathlon.com
Last edited by:
Ale Martinez: Oct 26, 11 7:37