Pendulum and damping

Plumb bob is actually a type of pendulum.

Movement is determined by Simple harmonic motion

period of the pendulum was approximately 

2*Pi*sqrt(l/g)

Damping and critically damping 

Water vs air:

40 sec vs 60 sec 

Dry and viscous damping

Flapping of bird pendulum 

By air

Diameter of string 

Helm string麻繩 vs nylon line: 40 sec vs 70 ~80 sec

Eddy current and Magnetic damping

Reinventing ideas 

Initial experiment with an existing plumb bob and two simple magnets is not too successful, needs more fine tuning. Otherwise you are making a chaotic pendulum instead. TBD.

Another YouTube 

Xmdemo by varying the magnet to damper distance

Magnetic braking(eddy current) with copper plate:

ME230

Reverse "Laser" plumb bob, laser firing upwards

Laser firing downwards：

Shinwa ， 易之力 EZX-038

Sikana , using a wooden block with hole

Plumb bob should be as close to wall as possible, almost touching.

Stackexchange

Isaac

Plumb bobs , storable 

Constructor org

Temple builder

Smartbob

Curso albanilera

Primar pilar

Magnetic damping line for ship patent 

How to thread 

Tuned mass damper in buildings and suspension bridges

In Tamiya 4WD 

1.2mm  masonry cord, polyethylene meister brick line