# Speeding up Integrate and the numerical solution

I want to compute the drag of a plate

Below is the code I am using to integrate the function

velcenter = {dotx, doty, 0};
r = {Cos[θ[t]], Sin[θ[t]], 0};
veltanA = {-Sin[θ[t]], Cos[θ[t]], 0};
velxpoint = Part[Cross[velcenter, r], 3];
dragD = 1/2*ρ*cofD*h*Integrate[(Abs[velxpoint - s*dotθ])*(velcenter +
s*dotθ*veltanA), {s, a - l, a}];


The integration is so slow and I want to speed it up. Any suggestions are welcome !

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conbine the Abs functon and the integrate function .the runing time is unbelievable – Ann Feb 26 '14 at 8:41
Is your integrand intended to be a scalar or a vector ? – b.gatessucks Feb 26 '14 at 8:49
integrand is a vector,3-D – Ann Feb 26 '14 at 13:29
The difficulty lies in the integral variable in Norm function,it makes the running time longer – Ann Feb 28 '14 at 1:06