Is there "not...till"? Does its meaning equal to "not...until"? Does the sentence "A body at rest will not move till a force is exerted on it" sound natural?
till is a synonym of
until, so the meaning is the same, yes.
Until is the more standard word.
It can also be written
til. (Both are less formal than
Edit: Note that
until is the preferred word today, so
until will usually sound most natural. Other meanings of
till are even included in this graph: