Piston Question that I do not understand

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[SOLVED] Piston Question that I do not understand

Homework Statement

A block rides on a piston that is moving vertically with simple harmonic motion.
(a) If the SHM has a period 1.0s, at what amplitude of motion will the block and piston separate?
(b) If the piston has an amplitude of 5.0cm, what is the maximum frequency for which the block and piston will be in contact continuously?

The attempt at a solution

I don't understand the question. What is a piston, what causes the block to separate, how do I start the question?

 

[LandOfStandar]

I searched it more and got an answer