Why not look at the words themselves?
Cool: low temperature... calm, easy, effortless
Awesome: some awe! ...awe-inspring, fascinating
Smashing: something exciting... like a car smash. Or smashing plates.
Groovy: in a groove. Like the grooves on a vinyl record. Also a groove has a direction, so you'd guess whatever's in the groove (and therefore groovy) is going somewhere.
It's fun to work out the analogy. :D