How To Remove Bounce When Bouncy Objects Encounter Bounciness

June 30, 2026 by Maya Posch 7 Comments

We all love a good bit of bounce now and then, with everything from trampolines to bouncy castles and bouncy balls forming the staple of a wholesome childhood for many. That said, most of our bouncy experiences in day to day life concern bouncy objects that meet immovable or rigid objects, including said child having a blast in a bouncy castle. Where the physics get arguably more interesting and less intuitive is when you combine two objects that are both bouncy, with [Steve Mould] recently taking a look at the tuning of said bounciness to even kill the bounce completely.

Understanding how to achieve this tuning means understanding how the kinetic energy is stored in each flexible material, and how to dissipate it in a way that doesn’t result in the aforementioned bounciness. In the simple physical demonstration setup the addition or removal of weights to the lower sprung platform tunes the response to the bouncy ball that is dropped on top of it.

After going through the science behind bounciness and springiness using the practical application of this science in the context of golf balls and clubs, [Steve] introduces the simulation tool that he created. This allows you to tweak the parameters of such a double spring system, which may bring back some high school physics lessons for some.

In a system like that of a golf club and the ball, having undesirable oscillations (bouncing) reduces the final kinetic energy transferred to the ball. Although ‘bouncy’ is perhaps not the first thought that comes to mind when handling a golf ball or a club, ultimately they are just as bouncy as a bouncy ball or an electric switch, just on their own scales, with their own opportunities for optimization and analysis.

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Hams Watch For Meteors

March 28, 2023 by Bryan Cockfield 13 Comments

After passing an exam and obtaining a license, an amateur radio operator will typically pick up a VHF ratio and start talking to other hams in their local community. From there a whole array of paths open up, and some will focus on interesting ways of bouncing signals around the atmosphere. There are all kinds of ways of propagating radio waves and bouncing them off of various reflective objects, such as the Moon, various layers of the ionosphere, or even the auroras, but none are quite as fleeting as bouncing a signal off of a meteor that’s just burned up in the atmosphere.

While they aren’t specifically focused on communicating via meteor bounce, The UK Meteor Beacon Project hopes to leverage amateur radio operators and amateur radio astronomers to research more about meteors as they interact with the atmosphere. A large radio beacon, which has already been placed into service, broadcasts a circularly-polarized signal in the six-meter band which is easily reflected back to Earth off of meteors. Specialized receivers can pick up these signals, and are coordinated among a network of other receivers which stream the data they recover over the internet back to a central server.

With this information, the project can determine where the meteor came from, some of the properties of the meteors, and compute their trajectories by listening for the radio echoes the meteors produce. While this is still in the beginning phases and information is relatively scarce, the receivers seem to be able to be built around RTL-SDR modules that we have seen be useful across a wide variety of radio projects for an absolute minimum of cost.

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Robotic Ball-Bouncing Platform Learns New Tricks

June 30, 2021 by Donald Papp 11 Comments

[T-Kuhn]’s Octo-Bouncer platform has learned some new tricks since we saw it last. If you haven’t seen it before, this device uses computer vision from a camera mounted underneath its thick, clear acrylic platform to track a ball in 3D space, and make the necessary (and minute) adjustments needed to control the ball’s movements with a robotic platform in real time.

We loved the Octo-Bouncer’s mesmerizing action when we saw it last, and it’s only gotten better. Not only is there a whole new custom ball detection algorithm that [T-Kuhn] explains in detail, there are also now visualizations of both the ball’s position as well as the plate movements. There’s still one small mystery, however. Every now and again, [T-Kuhn] says that the ball will bounce in an unexpected direction. It doesn’t seem to be a bug related to the platform itself, but [T-Kuhn] has a suspicion. Since contact between the ball and platform is where all the control comes from, and the ball and platform touch only very little during a bounce, it’s possible that bits of dust (or perhaps even tiny imperfections on the ball’s surface itself) might be to blame. Regardless, it doesn’t detract from the device’s mesmerizing performance.

Design files and source code are available on the project’s GitHub repository for those who’d like a closer look. It’s pretty trippy watching the demonstration video because there is so much going on at once; you can check it out just below the page break.

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Juggling Machine Listens To The Bounce To Keep Ball In The Air

July 25, 2018 by Dan Maloney 10 Comments

It’s a seemingly simple task: bounce a ping-pong ball on a wooden paddle. So simple that almost anyone can pick up a ball and a paddle and make a reasonable job of it. Now, close your eyes and try to do it just by the sound the ball makes when it hits the paddle. That’s a little tougher, but this stepper-driven platform juggler manages it with aplomb.

That’s not to say that the path to the finished product in the video below was a smooth one for [tkuhn]. He went through multiple iterations over the last two years, including a version that surrounded the juggling platform with a fence of phototransistors to track where the ball was at any time. That drove four stepper motors through a cross-linkage that popped the platform up at just the right moment to keep the ball moving, and at just the right angle to nudge it back toward the center of the platform. The current version of the platform does away with the optical sensors in favor of four small microphones. The mics pick up the sharp, well-defined sound of the ball hitting the platform, process the signal through an analog circuit, and use that signal to trigger a flip-flop if the signal exceeds a setpoint. An Arduino then measures the time delay between arriving signals, calculates the ball’s position on the platform, and drives the steppers through a PID loop to issue the corrective bounce.

The video below is entrancing, but we found ourselves wishing for a side view of the action too. It’s an impressive build nonetheless, one that reminds us of the many maze-runner and Stewart platform robots we’ve seen.

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Microswitches: Past The Tipping Point

April 17, 2017 by Dan Maloney 46 Comments

You find them everywhere from 3D printers to jet airliners. They’re the little switches that detect paper jams in your printer, or the big armored switches that sense when the elevator car is on the right floor. They’re microswitches, or more properly miniature snap-action switches, and they’re so common you may never have wondered what’s going on inside them. But the story behind how these switches were invented and the principle of physics at work in the guts of these tiny and useful switches are both pretty interesting.

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The Reason Dead Batteries Bounce

September 5, 2014 by Brian Benchoff 23 Comments

For the last few years, very well-informed people have been able to tell if an alkaline battery is good or not simply by dropping them. When dropped from an inch or two above a hard surface, a good battery won’t bounce, and will sometimes land standing up. A dead battery, on the other hand, will bounce. Thanks to [Lee] and a few of his friends, we now know why this happens.

While hanging out with a few of his buddies, [Lee] was able to condense all the arguments on why dead batteries bounce to two theories. The first theory, the ‘bounce theory’ said dead batteries had an increase in outgassing in the battery, increasing the pressure in the battery, which increases the spring constant of the battery itself. The second theory, the ‘anti-bounce theory’, said the gel-like properties of the electrolyte worked as a sort of mass damper.

[Lee] designed an experiment to test the outgassing ‘bounce theory’ of bouncing batteries. Instead of dropping a battery, an object – in this case a brass slug – was dropped onto both good and bad batteries. There was no difference. Even after holes were drilled to vent any gasses inside the battery, the brass slug bounced off both good and bad batteries the same way.

This means the reason dead alkaline batteries bounce is due to the electrolyte. [Lee] cut open a few AA cells and found the electrolyte in a good battery was a mushy mess of chemicals. In the dead battery, this same electrolyte hardened into a solid mass. [Lee] compares this to an anti-bounce hammer.

Finally, more than a year after most of us learned about bouncing dead batteries thanks to [Dave Jones]’ video, we have an answer. It’s a chemical change in the electrolyte that turns it from a goo to a solid that makes dead batteries bounce.

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Bounce Flash In Multiple Mediums

March 11, 2011 by Mike Szczys 5 Comments

[Nigel’s] been trying out a series of designs and materials to make his own bounce flash. He set out on this mission because most of the images he used flash on ended up washed out with dark shadows. The flash add-on seen above seeks to curb the harshness of the direct light but shielding the subject.

What you see above is just a couple of pieces of paper. [Nigel] put together a template so that you can cut your own. Although the design is his favorite, he also put together a second generation that is built from hobby plastic with a piece of aluminum tape as the reflecting surface. The main link at the beginning of this feature leads to that version, but after the break we’ve included direct links to each article he published during his experimentation.

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