The world has changed. I feel it in the water. I feel it in the earth. I smell it in the air. Or I smell something, for sure. In any case: world, changing, etc. The stumpshaker is 10 years old. Smart phones have taken over the earth. Could a smart phone shake large objects? Could I have the stumpshaker in my pocket?

This app requires the phone to be securely attached to a large, firm object to be shaken. The phone will shake, and then with the accelerometer measure any movement of the phone taking place after its own vibrating motor has stopped. Detected shaking is presumed to be taking place in the large object to which the phone is affixed.

Test shakes by the phone will change gradually over a large range, with the idea that when the resonant frequency of the attached object is reached, maximal post-shake vibrations will be detected. Once this frequency is known, the phone can add energy at the correct part of the resonant cycle, shaking the attached object more and more.
-- bungston, Mar 09 2016

Stump shaker Stump_20Shaker
The parent [bungston, Mar 09 2016]

Is that a stump shaker in your pocket?...
-- 2 fries shy of a happy meal, Mar 09 2016


The problem (although I hate to start out by raising a problem) is damping. For something like a tuning fork, there is very little damping, and therefore very small input vibrations at the right frequency can build up large resonances.

However, a tree is considerably more damped than a tuning fork: the trunk isn't as perfect a spring; the crown has massive air resistance; et soforth.

But, on the other hand, if there are any carbon- fibre trees growing in a vacuum, this would work.
-- MaxwellBuchanan, Mar 09 2016



random, halfbakery