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# Mass Spring - Phase and Time Period watch

1. Hey,

Has anybody got any experiment reports/details on this experiment that we need to learn?

Where you measure the time it takes for two masses on springs to become in phase from release?

Thanks
2. Always use a fiducial mark. Always 0.o.
3. But can you explain why when two different masses oscillate, they go from being in phase to out of phase, and then back into phase?

Eg.

1) 500g mass on spring
2) 200g mass on spring

They start in phase, then go out of phase, and then back into phase, which you can measure as t, and plot against m, which gives a curve, but how does the time taken to become in phase relate to the time period of the system?

Thanks
4. If the one mass has a frequency of, say, 5 oscillations per second, and the other has a frequency of, say, 7 oscillations; then they will be in and out of phase twice per second.
The reason?
The formula is that this frequency (called the "beat" frequency) is always equal to the difference between the two. In this case 7Hz -5Hz = 2Hz
If this frequency is 2 Hz, then the period, T, is 1/f which gives 1/2 seconds.
So the two masses will be in and out of phase every 1/2 a second.
The frequency of a mass on a spring depends on the mass (as well as other things), so the time taken to get out of phase and back in again will depend on the masses on the two springs.

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Updated: February 8, 2010
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