Gear ratio Definition and 52 Threads

Hi, I am doing a project that involves an electric motor that winches an object upward pulling it by a string, over a given distance and I need help to calculate an optimal gear ratio, if that is possible. This is how far I have got... Variables torque/rpm gear ratio Constants distance...

I have heard that this concept is already starting to be implimented in cars (constantly changing gear ratios), is this true?