How to write a Q with a dot above, for differential notation?
Q̇ can be made a part of keyboard input using the replace. 

Then when you type your chosen word it will be replaced with the Q̇. 

Here is a sample: I have chosen to call it qdot (genius :)

You can find another Q̇ on the web and use it (Paste) instead.



So now when ever you type "qdot" it will be replaced with your symbol. (works in most applications)