Resonance

Natural Frequencies All objects have certain frequencies that it vibrates at with the lowest amount of resistance. This is called the natural frequency In other words, it is the frequency something likes to vibrate at. Several things have more than one natural frequency

Resonance When something vibrates at the natural frequency of another object, the second object will begin to vibrate with a much larger amplitude than through a normal forced vibration. This is resonance. The objects do NOT need to be touching for this to work (only connected by air)

Wine Glass Wine glasses also have natural frequencies. Flick the glass, or run your finger across the top and you will hear it. If you are capable of singing exactly at that note (natural frequency) you can resonate with the glass. This will cause the glass to vibrate (shake) If you can get enough power behind your voice you can shatter the glass. mythbusters

How this effects you Older cars that tend to shake at certain speeds For several cars you will find it is not high speeds but certain speeds or more importantly certain vibration rates of your engine resonating with your car. As the car gets older the structure changes slightly (dents, nuts and bolts fall out) this allows for natural frequencies you don’t want. If it just shakes at high speeds then it is not resonance.

Bridges Natural frequencies and resonance can get very dangerous with bridges. If the bridge shakes too much it could collapse. Bridges can have natural frequencies similar to earthquakes. The Tacoma Narrows Bridge “Galloping Girdie” was an ugly example. Gallop Twist Fall Gallop TwistFallGallop TwistFall

Other Examples of Resonance