(つ◔౪◔)つ━☆゚.*・。゚ The 2023 TKSST Gift Guide ✩°。⋆・゚  
Get smart curated videos delivered to your inbox.   SUBSCRIBE
The Kid Should See This

Angular momentum demo with a Hoberman Sphere

Watch more with these video collections:

Hoberman spheres, invented by Chuck Hoberman, are beautifully engineered icosidodecahedrons that are fun to expand and contract. This one can be contracted by pulling a string.

As it turns out, a Hoberman sphere is also an excellent tool for demonstrating the conservation of angular momentum. In the video above, Utah State University’s Professor Boyd F. Edwards spins the expanded sphere, then pulls a string to contract it, causing “the sphere’s moment of inertia to decrease and its angular speed to increase.” From Khan Academy:

Angular momentum depends on the rotational velocity of an object, but also its rotational inertia. When an object changes its shape (rotational inertia), its angular velocity will also change if there is no external torque.

In The Physics Of Figure Skating, Science Friday explains further:

Once a skater leaps into the air, they’re stuck with however much angular momentum they’ve created. But a skater can change one thing: the moment of inertia. Moment of inertia determines how easy it is for an object to speed up or slow down, and describes the resistance that a force is working against. A larger moment of inertia—like when a skater extends their arms—will result in a slower rotational speed. But a smaller moment of inertia—like when a skater hugs their arms into their body tightly—will lead to a faster spin.


Watch more physics demonstrations on this site, including Demonstrations of the Coanda Effect, observing the angle of repose with DIY physics devices, Newton’s Beads, and how to make a self-starting siphon.

via Reddit.

🌈 Watch these videos next...

Why don’t perpetual motion machines ever work?

Rion Nakaya

Why do spinning rings & spinning disks have different paths?

Rion Nakaya

Which ball will race to the bottom first?

Rion Nakaya

What on Earth is spin?

Rion Nakaya

What happens to balloon animals in liquid nitrogen?

Rion Nakaya

What happens to a flame in an electric field?

Rion Nakaya

What happens inside an artificial gravity lab?

Rion Nakaya

Weight distribution on light bulbs and eggs, a physics demonstration

Rion Nakaya

Water powered hammer (Monjolo) – Primitive Technology

Rion Nakaya