Accepted Answer
We know that there is a formula velocity = frequency x wavelength for all types of waves.If we assume one complete oscillation of a pendulum to be wavelength we can apply the above formula for the pendulum too. So as v = fλ and f = v/λ we can just plug in the values to get our answer of frequency.So frequency = 30/0.35 which is equal to 85.17 Hertz (Hz).
Suggested Answer
I think you're trying to take the formulas for speed, wavelength, and frequency of a wave, and apply them to a pendulum. You can't do that. It doesn't work.A pendulum is moving in 'simple harmonic motion', not wave motion. It's speed is continuously changing, from zero at both ends of its swing, to maximum as it passes through the 'rest' position at the bottom. And there's no wavelength defined for a pendulum ... if you're thinking that it could be the distance from end to end of its swing, or maybe half of that, you should know that the frequency of an ideal simple pendulumis not related to that distance at all.Finally, in the real world, the numbers in this question really kind of don't make any sense. You have a structure where some part of it is roughly a foot long (0.35m = 13.8 inches), and at least at some point during its swing, something is moving at 30 m/s ... about 67 mph ! If something like that could even stay on the table, and IF its frequency were (speed/wavelength) ... like a wave's frequency is ... then its frequencywould be (30 / 0.35) = 85.7 Hz ! ! The thing would be wiggling back and forth every 0.017 second ! It would need to be operated only inside a bomb shelter, with all personnel withdrawn beyond a safe perimeter before it flies apart and scatters shrapnel everywhere.
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