A test tube of zinc oxide
Answer:
Whether you get the metal or hydrogen during electrolysis depends on the position of the metal in the reactivity series: the metal will be produced if it is less reactive than hydrogen. hydrogen will be produced if the metal is more reactive than hydrogen.
Umm...Well...
Heisenberg's Uncertainty Principle says that we can never know both the position and rate of change of a particle at any time. We can only know one or the other. This leads to rather silly jokes that deal with uncertainty, probability, and superposition. So, saying that "Heisenberg may have slept here" is essentially saying that it is uncertain if Heisenberg slept there or not, making for a rather silly, but slightly unfunny physics joke.
Static Friction, Sliding Friction, Rolling Friction, and finally Fluid Friction.
