It can't be seen, can't be felt, can't be heard and can't be smelt. It lies behind stars and under hills, and empty holes it fills. It comes first and follows after, ends life and kills laughter. What is it?
You put a glass of water on a record turntable and begin slowly increasing the speed. What happens first -- does the glass slide off, tip over, or does the water splash out?
(The 'Google Riddles' are interview questions those who wish to get hired were asked).
Depends on the amount of water in it.
A glass with almost no water will not spill, while a glass almost full will spill and also fall off probably due to the weight of the water going off. In other words - there is no way to tell without knowing the amount of water in the glass.