Why We Rattle Things That Are Stuck?

[mrmonkah]

Im studying Classical Physics and currently covering resonance, one question i got thinking about was why we rattle things that are stuck.

Am i right in thinking that we apply a resonance to the natural frequency of the stuck object in order to magnify it's amplitude and hence give our selves room to remove the object?

Not very well communicated on my part, but is my reasoning sound?

Cheers,

Dan

 

[zhermes]

Meh; i think that might be part of it in some cases----definitely the main reason is just to break static friction, and get things off ledges/hangups/etc. You're also taking a stochastic approach---hoping that the object will just kind of eventually find its way out if you force it to explore enough of the space.

 

[mrspeedybob]

Rattling two things together can generate huge forces between them.

One example I am familiar with is an impact wrench used by mechanics for tightening and loosening nuts & bolts. There is a rotating mass inside the tool which intermittently engages the output shaft. Angular momentum is transferred almost instantly to the shaft and then to the nut. Since the transfer happens over a very short distance the force involved is huge. The result is that you can apply several hundred foot pounds of torque to a fastener with only very minimal reaction torque applied to the tool.

Other, less precisely engineered forms of rattling will accomplish the same thing.

 

[Danger]

In simpler situations, rattling or tapping with a hammer can just break loose crud such as rust that is hindering movement.