Question in new way phy for AL

2010-02-22 2:17 am

On page 288
If the driving frequency is much lower than the natural frequency of the system, the system will oscillate nearly in phase with the driving force.
If the driving frequency is much higher than the natural frequency of the system, the system will oscillate nearly out of phase with the driving force.

But on page 289
The short pendulums are nearly in phase with the driver pendulum, while the long pendulums are almost out of phase with the driver pendulum.

my question:
As T = 2pi (l/g)^0.5
and frequency = 1/T ,
then if the length(l) of the pendulum string is shorter, then the natural frequency should be higher. Then why the short pendulums are nearly in phase, instead of out of phase, with the driver pendulum ?

回答 (1)

天同

2010-02-22 5:46 am

✔ 最佳答案

I don't have the book, so I just give the answer based on your description.

You have said:
If the driving frequency is much lower than the natural frequency of the system, the system will oscillate nearly in phase with the driving force.

then if the length(l) of the pendulum string is shorter, then the natural frequency should be higher.

That means the driving frequency is lower than the high natural frequency of the system, the two systems will oscillate in phase .

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