# Foo - Physics Help Please?

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View Full Version : Physics Help Please?

BenLi
01-20-08, 10:21 PM
A cubical block vibrates horizontally, in Simple Harmonic motion (SHM) with an amplitude of 8.0 cm and a frequency of 1.5 Hz. If a smaller block sitting on it is not to slide, what is the minimum value that the coefficient of static friction between the two blocks can be.

Can anyone help?

EJ123
01-20-08, 10:35 PM
Message Phantomcow2. He'll know.

stevesurf
01-20-08, 10:37 PM
In Coulomb Damping (http://en.wikipedia.org/wiki/Coulomb_damping), the frictional force each of the object's experience are opposite each other and equal. The Coefficient of static friction of the smaller object x the Normal Force (smaller object's weight) = the Frictional Force.

Find the equation that relates Force, Amplitude and Frequency of the larger object and solve for the Coeff. of Static Friction.

ElJamoquio
01-20-08, 10:52 PM
1. Figure out the acceleration with simple harmonic motion.

x = sin(wt)

Take the double derivative and find the mzximum. Hint, it should be really easy.

2. Figure out the force.

F = m*a = coefficient of friction * m

BenLi
01-20-08, 11:25 PM
thanks for the help all. I've solved it. Here's the solution in case you were curious.

http://i214.photobucket.com/albums/cc232/ben_li/Physics-2.jpg