Rattleback (celt)
A rattleback (celt) spins smoothly one way but wobbles and can reverse when spun the other — a signature of chiral geometry and friction coupling spin to rocking modes. This simulator is an intentional cartoon: a small coupled ODE ties spin rate to lateral rocking so students can see how “wrong-handed” rotation feeds energy into oscillation. It is not a full asymmetric-top integrator with realistic contact patches.
Who it's for: Introductory rigid-body curiosity demos; pair with a real tabletop celt if available.
Key terms
- Rattleback
- Chirality
- Spin reversal
- Friction coupling
- Toy model
How it works
A rattleback’s curved footprint couples spin and sideways rocking. This is a cartoon ODE, not a full rigid-body integrator — use it to show why one rotation sense dies out and flips.
Frequently asked questions
- Can I read quantitative reversal times from this page?
- Only qualitatively. Parameters are tuned for visible reversal on a laptop screen, not calibrated to a specific celts dimensions or μ.
- What should I say in class about the real toy?
- Mention that curvature asymmetry and sliding vs rolling at the contact line matter; many articles derive conditions for instability of steady spin about the intermediate axis of inertia.
More from Classical Mechanics
Other simulators in this category — or see all 84.
Maxwell Wheel
Disk on a thin axle unwinds string: shared linear and rotational kinetic energy from falling potential, a ≈ g / (1 + I/(mr²)).
Brachistochrone Race
Beads race down a line, a circular arc, and a cycloid with v = √(2gy); the cycloid wins the descent-time minimum.
Coupled Pendulum Chain
N pendula with neighbor springs in θ: watch traveling waves and reflections after a center kick.
Sliding Ladder
Frictionless wall and floor: θ̈ = −(3g/2L) cos θ; released from rest, wall contact is lost when sin θ = (2/3) sin θ₀.
Angle of Repose
1D sandpile lattice: avalanches relax until slopes stay below μ = tan α — compare the green guide line.
Cart & Inverted Pendulum
Horizontal force on a cart with a hinged rod: coupled (M+m)ẍ and mL²θ̈ integrated for manual balancing.