Supersized Slow-Mo Slinky Drop
Why Physics Stack Exchange recommends it
Physics Stack Exchange answerers link it as a vivid demonstration that changes in force propagate through a medium at finite speed, and that real springs have mass in every coil.
Recommended by 4 people across 4 different months, 2016 to 2022.
What it is
A short Veritasium clip showing a very long slinky being dropped and filmed in slow motion. The top of the slinky starts falling while the bottom stays hovering in place until the collapse wave reaches it.
What people said
Recommends CR Drost · 2016-12 · Physics Stack Exchange · on “Speed of gravity (water balloons)”
You may also like to watch this video [this video] where a very long "slinky" toy has a similarly counterintuitive behavior when you look at it in slow motion, but ultimately in both cases you can reason out that it's simply obeying Newton's laws, there is no "speed of gravity" that affects these situations. (The speed of gravity is in fact the same as the speed of light and is much, much faster than any of the things happening in these videos.)
Recommends Dale · 2020-08 · Physics Stack Exchange · on “Is the effect of friction force transferred INSTANTLY in this case?”
Does it mean that the effect is transferred INSTANTLY and if not can we calculate the delay ?? Well, there is more than one effect, and different effects happen at different times. First, instantly when you release the friction on the rope the center of mass of the system consisting of the rope + the bob begins to travel tangentially. Second, the tension in the part of the rope immediately adjacent to your hand begins to relax. This relaxation of the tension propagates as a longitudinal wave through the material of the rope. The speed of propagation of this wave is the speed of sound in the material of the rope. Third, the bob will continue to move in the circular path until that mechanical
Recommends mmesser314 · 2021-08 · Physics Stack Exchange · on “Is it impossible to stretch or compress a spring with a force other than $kx$?”
You are right. But keep in mind this problem is idealized so you can focus on the physics in your current chapter, without extra complications. Such problems often use perfect, massless, frictionless pulleys and springs. They often have everything at rest. The reason is to avoid introducing precisely the kind of complication you have discovered. If you compress/stretch an ideal spring a distance $x$ , it will push/pull back with a force $kx$ . A real spring has more possibilities. For example, see the Veritasium videos How Does A Slinky Fall? [LINK] and Supersized Slow-Mo Slinky Drop [this video] . In a real spring, each coil has mass. Different forces can be applied to different coils. Each coil
Recommends rob · 2022-06 · Physics Stack Exchange · on “Behavior of a loose coin on a free fall ride”
Suppose the penny is sitting on a thigh, and the thigh is sitting on a seat, and the seat is sitting on some shock absorber, and the shock absorber is sitting on the frame of the cart, and the exciting part of the ride is that the cart goes into free fall when some support is removed. All of these pieces have some degree of elastic compressibility. The squashiest ones are the thigh and the shock absorber, but they are all a little compressible. Prior to the release, each little vertical slice of this pile was the equilibrium with the pieces above and below it. No little piece of this pile will start to accelerate downwards until the force from below has changed. The information that the floo