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# Simple physics problem

Posted 9 years ago
 Greetings all. I just got my son the Pro version to help him in college but he, and I, am having a lot of trouble figuring out how to word and enter problems. For example: A projectile fired from the ground with the following parameters: Weight of projectile: 3Kg Initial velocity: 250 m/s Angle of launch: 53 Deg. How would something like this be entered? I have looked at examples and am still confused.
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Posted 9 years ago
 Following is a solution of the problem. It requires calculus and some knowledge of Mathematica programming. In:= g = 9.81; In:= (* m value is arbitrary! *) In:= (* components of initial velocity *) In:= (* x'=250 Cos[53\[Degree]] *) In:= (* y'=250 Sin[53 \[Degree]] *) In:= (* x-motion at constant velocity *) In:= x[t_] := 250 Cos[53 \[Degree]] t In:= (*Newton's law for y-motion m y''[t]=-m g*) In:= DSolve[{m y''[t] == -m g, y == 0, y' == 250 Sin[53 \[Degree]]}, y[t], t] Out= {{y[t] -> 199.659 t - 4.905 t^2}} In:= y[t_] := 1/2 (-g t^2 + 500 t Cos[37 \[Degree]]) In:= Solve[y[t] == 0, t] Out= {{t -> 0. + 0. I}, {t -> 40.7052}} In:= ParametricPlot[{x[t], y[t]}, {t, 0, 40.7052}] Output is plot of parabola 
Posted 9 years ago
 Wow. I never would have figured that out. Even with the solution, I have no idea how to enter this into Wolfram.