Mechanical Energy-related

For an introduction to the phenomenon of 'Parametric Excitation' where, instead of driving a system directly, energy — and typically(?) less energy — is put into modulating one of the oscillator's parameters resulting, e.g., in much larger oscillations than one might typically expect.

Bruce Denardo, Physics Department, Naval Postgraduate School (2019). Physics Lecture Demonstration: Parametric Excitation. YouTube video, available from youtube.com/watch?v=2xyFvcPvLfw

Bruce Denardo, Physics Department, Naval Postgraduate School (2019). Physics Lecture Demonstration: Parametric Instability. YouTube video, available from youtube.com/watch?v=dGE_LQXy6c0

Veljko Milkovic. Hand Water Pump with a Pendulum. Web page. Accessed October 2023, available from veljkomilkovic.com/rucnaPumpaEng.html

Veljko Milkovic Official Video Channel (2011). Pendulum eases pumping of water. YouTube video. Available from youtube.com/watch?v=jNdF8mTfu4g

From the video's description:

Veljko Milkovic demonstrates a new design of his hand water pump with a pendulum where it is possible to use a little finger for pumping.

Hand water pump with a pendulum is very simple solution for pumping water. It provides alleviation of work, because it is enough to move the pendulum occasionally with a little finger to pump the water, instead of large swings. Work is alleviated because easier, long-lasting and effortless use of the hand water pump has been enabled. Input energy for starting the process of pumping, in form of occasional pushing of the pendulum, is much less than with typical hand pumps. The advantage of this invention compared to present hand pump solutions are: less force to start the pump, less water consumption, both arms can be used to fetch the water.

To get the water running out of the pump, the pendulum needs to be out of balance. After that, based on gravitational potential, the piston starts oscillating and the continuous stream of water is coming out of the output pipe. The pendulum should be occasionally pushed, to maintain the amplitude i.e. the stream of water. Using the minimum of human strength in comparison to present classic hand water pumps enables efficient application in irrigation of smaller lots, for water-wells and extinguishing fires even by old people and children, which was proved by a large number of interested future consumers during the presentations.

For footage of a larger version in action, see youtube.com/watch?v=hNpgl7o_1QI; for commentary on this video by Veljko Milkovic, see youtube.com/watch?v=M6xLglhs3rs&t=1483s. For an updated design from 2022, see youtube.com/watch?v=7wn15yJ9JYY.

Veljko Milkovic Official Video Channel (2011). Pendulum-Lever System Better Than Simple Machines. YouTube video. Available from youtube.com/watch?v=M6xLglhs3rs

As well as providing some corrections and additional context about the demonstration shown in youtube.com/watch?v=hNpgl7o_1QI, this video also demonstrates a few more applications of the two-stage mechanical oscillator.

Veljko Milković Research and Development Center. Two-stage mechanical oscillator. Web page. Accessed October 2023, available from vemirc.com/en/oscillator

Veljko Milković Research and Development Center. Patents of Veljko Milković. Web page. Accessed October 2023, available from vemirc.com/en/patents

Veljko Milković Research and Development Center. Physics of the Two-Stage Mechanical Oscillator. Web page. Accessed October 2023, available from vemirc.com/en/theory-maths

Veljko Milković Research and Development Center. Replicas of the Two-Stage Mechanical Oscillator. Web page. Accessed October 2023, available from vemirc.com/en/replicas