Some time ago I posted a bunch of Creative Commons licensed physics drawings that I made for class. I've added several more drawings and posted them as a page here, where I intend to keep adding more of them.
The thumbnails don't really show the full resolution of the drawings. You'll have to open up the files and export the drawings at whatever resolution you need.
I hope these are useful to instructors (or anyone, really) which is why I'm using the CC licence to encourage people to make use of them. Let me know if you find them useful, and if you make improvements to them, please share them with us (that's the ShareAlike part of the licence).