Vibration Platform: Find Frequency for Rock Clatter

[gonzalo12345]

Homework Statement

A vibration platform oscillates up and down with an amplitude of 10.4 cm at a controlled variable frequency. Suppose a small rock of unknown mass is placed on the platform. At what frequency will the rock just begin to leave the surface so that it starts to clatter?

Homework Equations

I need to know how to start this problem and what equations to use

The Attempt at a Solution

 

[tiny-tim]

A vibration platform oscillates up and down with an amplitude of 10.4 cm at a controlled variable frequency. Suppose a small rock of unknown mass is placed on the platform. At what frequency will the rock just begin to leave the surface so that it starts to clatter?

Hi gonzalo12345!

This is like a roller-coaster problem … the rock will lose contact when the platform is accelerating downward so fast that the rock cannot fall fast enough to keep up!

So work out the maximum acceleration of the platform (it will depend on frequency, obviously).