waves Q - kaplan

[amar21]

a battery powered motor drives a pendulum at its natural frequency in order to insure that the pendulum swings at a constant rate. If the same motor is to be used on a longer pendulum, should the frequency of the motor be adjusted, and if so, then should it be increased or decreased?

i figured angular frequency = root g/l... increasing L would mean we have a smaller frequency, so we should increase the freq to keep it at the constant rate

however, the answer says we decrease the frequency

any input?

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[HawkeyePostOp]

They're not really "keeping" anything at a constant rate.

It's a much simpler problem - pendulum 2 has a longer length, thus a longer period, than pendulum 1.

Thus the pendulum's frequency must be lower, and thus the motor's frequency must be adjusted down.