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Loren Booda
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A frictionless system consists of a swing of given length and its massive rider, initially at rest. Is it possible for the rider to kick this system into its unforced natural frequency?
Originally posted by HallsofIvy
Without friction, so that all forces are internal, then "conservation of momentum" says that we cannot change the momentum of the system by inside forces.
Ie, a kid sitting on a swing.Originally posted by krab
We now have a compound pendulum...
That really doesn't make a lot of sense. It sounds like you are saying the starting conditions are no internal or external motion or forces. It will just sit there then. Newton's first law.Originally posted by Loren Booda
My question again: for a frictionless pendulum initially at rest, can any movement "within" the bob, now having ceased, have caused the pendulum to continue at its nonzero natural frequency? This holds for a compound or a simple pendulum.
Yes, and the answer is yes. A pendulum not under continuous force can swing at only one frequency: its natural frequency.Originally posted by Loren Booda
(You may have already answered this.)
Now try the same without friction - that was my contention.I as well as many other kids could manipulate the swing from a dead stop to full swing without their feet touching the ground.
Where is this friction you are talking about? Wind resistance? Its not enough to get you moving.Originally posted by Loren Booda
Doc Now try the same without friction - that was my contention.
Whereso on the SODA website?I couldn't get one swinging at the swing's frequency; only at the muscle's frequency.
Originally posted by Loren Booda
I've seen something like it on cable TV where the the machines evolve. Very pleasing to the eye and visceral. Whereso on the SODA website?
However, can the (frictionless) swing remain in harmonic motion once the bob's rocking (started from a dead hang) has stopped?When a rider pumps a swing, s/he is mimicing this change in potential energy by raising and lowring the CM of the swing system. The change in PE MUST be reflected in a change in KE. Thus the simple act of rocking back and forth is sufficient to set a swing into motion. As long as the frequency of the CM change is harmonic with the natural frequency of the swing motion will occur.
Originally posted by Loren Booda
Integral, However, can the (frictionless) swing remain in harmonic motion once the bob's rocking (started from a dead hang) has stopped?
However, can the (frictionless) swing remain in harmonic motion once the bob's rocking (started from a dead hang) has stopped?
The concept behind a frictionless swing is to eliminate the resistance caused by friction in order to study the natural frequency of a pendulum-like motion.
A frictionless swing can be achieved by using a low-friction bearing or lubricant on the pivot point of the swing, as well as minimizing any other sources of friction such as air resistance.
Natural frequency is the frequency at which an object vibrates when disturbed from its equilibrium position. It is important to study because it allows us to understand the behavior of systems and predict how they will respond to different forces.
The factors that affect the natural frequency of a swing include the length of the swing, the mass of the rider, and the force applied to the swing.
The concept of a frictionless swing can be applied in fields such as engineering, physics, and biomechanics to study the behavior of different systems and optimize their performance. It can also be used to understand the effects of friction in real-world scenarios and how to minimize its impact.