A vibration platform oscillates up and down with a fixed amplitude of 8.1 cm and a controlled frequency that can be varied. If 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?

Question

Physics

Matthew

30 May, 20:51

A vibration platform oscillates up and down with a fixed amplitude of 8.1 cm and a controlled frequency that can be varied. If 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?

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Answers (1)

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Laci Nash · Answer 1

The rock will begin to leave the surface when reaction force becomes zero or when the acceleration of the plate-form downwards and gravitational acceleration acting on mass m becomes equal.

acceleration of plate - form (maximum) = ω²A, A is amplitude and ω is angular frequency.

ω²A = g

4π² n² = g

n² = g / 4π²

9.8 / 4 x 3.14²

=.2484

n =.5