Between Resonance and Natural Frequency?

Question

I am totally confused with this two terms-natural frequency and resonance...in my physics textbook it was stated resonance occurs when a system is made to oscillate at a frequency equilvalent to its natural frequency by an external force.The resonating system oscillates at its maximum amplitude....the effect of resonance can also cause damage.For exp,a bridge can collapse when the amplitude of its vibration increases as a result of resonance....I am confused..why resonance can cause damage yet it has the same frequency with the natural frequency?

I want to know whether resonance can apply additional force to a system so that the frequency of the system can achieved higher than its natural frequency....

Answer 1

It is a synchronization-accumulation of energy. To achieve resonance the forcing frequency and the natural frequency need to be the same. When they are also synchronized (do not need to be perfectly in phase, just have a phase margin wide enough from anti-podal--an oposite in phase for a stabilizing negative feedback) the forcing energy keeps adding to make the natural vibration grow in amplitude. When the sum of the forcing function and the damping factor (in a mechnical system) or the closed loop gain (in an electrical circuit) nets out greater than a unity gain, the system will blow itself up.

Answer 2

Natural frequency and resonant frequency are the same thing. However..... If you couple energy into, say, a bridge at a frequency above or below it's natural frequency, the amplitude of it's oscillations are rather rapidly damped out. But if energy is coupled at its natural frequency, the amplitude increases, with little loss, usually until something breaks.


Doug

Answer 3

IT CAN BECAUSE THE FREQUENCY FORCE CAN CHANGE AT ANY TIME DUE TO ITS MAG.