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paglia
Consider an object describing an elliptical path in the plane given by r (t) = (2 cos t, 6sin t), where t is in the interval [0, 2]. if the object is subjected to a field with a force given by the expression G (x, y) = (4xy, y^2), calculate the work done by G to move the object along the trajectory from (2, 0) to (0, 6), in direct order.
just not sure which expression will make easyer to calculate the dot product, paramtric or cartesian.
I tried parametric, though it would be easier.
Use Polar Coordinate x(t)= 2 cos(t) y(t)= 6 sin(t) P = 4 x y Q = y^2 Compute P(x(t),y(t)) x'(t) + Q(x(t),y(t))x'(t)=120 cos(t) sin^2(t) Integrate the last expression for t= to Pi/2 to obtain 40
This Q(x(t),y(t))x'(t) should be Q(x(t),y(t))y'(t)