# The Manipulate of this plot won't plot regarding projectile motion

It just plots a blank

    y[x_, \[Alpha]_, v_] = x*Tan[\[Alpha]] - 0.5*g*(x/(v*Cos[\[Alpha]]))^2

Manipulate[ Plot[y[x, \[Alpha], v] , {x , 0 , 10 }], {\[Alpha] , 0 , Pi/2 } , {v , 0 , 10} ] /. g -> 9.8


Honestly not sure why...maybe I'm just too tired to see the mistake.

• Manipulate[ Plot[y[x, \[Alpha], v] /. g -> 9.8, {x, 0, 10}], {\[Alpha], 0, Pi/2}, {v, 0.0000001, 10}] – march Aug 4 '16 at 19:37
• It still only plots a blank...do you think something is up with the kernel maybe? – Dylan Solms Aug 4 '16 at 19:41
• But thank you so much. I see where I made mistakes! – Dylan Solms Aug 4 '16 at 19:41
• Yeah, try quitting the kernel and trying again. It works fine for me. – march Aug 4 '16 at 19:42
• Cool! will do. So the function it is plotting is fine though? – Dylan Solms Aug 4 '16 at 19:43

You need to move the ReplaceAll into the 1st argument of Plot.
y[x_, α_, v_] := x*Tan[α] - 0.5*g*(x/(v*Cos[α]))^2