calculating r(t) and theta(t)

dopey9

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Jul 14, 2006
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i want to consider the motion of a fluid particle whose position at t=o is (x,y) =(1,0).

and i can use that dr/dt = u(r, theta) and rd(theta)/ dt = v(r.theta)

and i want to find r(t) and theta(t).

can anyone help me with this..like starting me off or something..if you can do this question can you please let me know thanks
 
i got the answer as

since x= rcos(theta) and y = rsin(theta) i worked out that

r(t) = ut + 1/cos(theta)

theta(t) = vt/r

can anyone verify that ..have i done it right??
 
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