NDSolve error inside Plot: $RecursionLimit :Recursion depth of 1024 exceeded

Questions
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1

hello, i have been trying to plot the maximum range for theta for a projectile motion experiencing linear drag, but i keep getting errors regarding the written code. when trying to transform y[t] to a function yy[t_] rather than the replacement rule there seems to be no wolfram language translation found and when rooting i get a message:$RecursionLimit
:Recursiondepthof1024exceeded.

tfinal[theta_]:=[s=NdSolve[{x' ' [t] == b x' [t] , y' ' [t] == -b y' [t] - g, x[0] == 0, y[0] == 0, x'[0] == v Cos [theta], y'[0] == v Sin[theta]}, {x,y}, {t, 0, 10}]; 
    yy[t_] := y[t] /. s[[1]]; 
    xx[t_] := x[t] /. s[[1]]; 
    xfinal[theta_]:=x[tfinal[theta]]
    plot[xfinal[theta], {theta,0.01,2.5}
2

Maybe this will help you a little

sol=Simplify[{x[t],y[t]}/.DSolve[{x''[t]==b x'[t],y''[t]==-b y'[t]-g,x[0]==0,y[0]==0,x'[0]==v Cos[theta],y'[0]==v Sin[theta]},{x,y},t][[1]]];
yy[t_]:=sol[[2]];yy[t]
xx[t_]:=sol[[1]];xx[t]

which displays

(g*(1-E^(-b*t)-b*t)+b*(1-E^(-b*t))*v*Sin[theta])/b^2

and

((-1+E^(b*t))*v*Cos[theta])/b
3
Open in Wolfram Cloud ↗

See here for More

Regards M.I.

4

it seems like whenever i include sol= at the beginning of the equation, i get this error
wwww.PNG

5

That looks like you’re trying to use the free-form input, which attempt to interpret natural language input. On Mac you get this by typing “Ctrl-=”, is that what you’re doing? What you want is just a plain input cell.

6

im not even on mac, and im using the online version of wolfram, but it seems to be using free format input none less