I'm new to Mathematica (literally started using it yesterday).
In one of the first calculations I'm using Mathematica for there is a variable with a subscript a_r, which means radial acceleration.
Unfortunately, there's also an equation for another variable, Orbital Radius, which is denoted r. Hence, whenever I attempt to write a_r, Mathematica automatically replaces the subscript with the equation for r.
Is there any way to stop it doing this?
I've attached an image of the problem.
Attachment: MathematicaProblem.jpg, URL: www.strath.ac.uk/space,