How to plot multiple equations / solutions on same graph?

Question

I've been working with physics and I want to plot the potential such that I can have multiple lines that represent multiple potentials. The equation is:

where V(r) is the potential, and I want to plot many lines so I can see the turning points of the graph. I'm pretty new to Mathematica, so I'm quite clueless. I tried using DSolve by differentiating V(r) and asking it to solve, and ContourPlot (though I suppose I'd have to turn it into a vector field first, which I don't know how and that was a bit of a random thing I tried). I also tried the normal Plot. I got blank graphs. Is it because I have undefined constants that are treated as variables, like l, M, ε? I'd really appreciate some help on what code I should use / what to do to have it plot out multiple lines for V(r) that represent the many possible solutions.

user740332 · Answer

You need give some number for your constants, I think that mathematica don´t plot with undefined constants. In this example I did $M=l=epsilon=1$
Plot[{1/(2 r^2), -(1/r^3), -(1/r) + 1/2}, {r, 0, 10}, PlotLegends -> "Expressions"]

Or you can put
M = 1; [Epsilon] = 1; l = 1
Plot[{l^2/(2 r^2), -((M*l^2)/r^3), -((M*[Epsilon])/r) + [Epsilon]/2}, {r,0,10}, PlotLegends -> "Expressions"]

And put the values of the constants that you want in the equalities of the first line

How to plot multiple equations / solutions on same graph?

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