Nutation

You might see a gyroscope “wobble” while precessing. It might look like the precession is unstable and “nods” up and down. Such “nodding” – let’s…

Spinning & precession

Why does a spinning toy top not fall over? How can a plate balance on a stick only when spinning fast? And why doesn’t the…

Newton’s 3rd law vs 2nd law

Newton’s 2nd law told us that unbalanced forces cause acceleration. But Newton’s 3rd law now tells that forces always come in pairs, equal but opposite…

Reaction forces

Take a step. You exert a stepping force on the ground. It is of course at an angle. The horizontal part $F_{\text{step}\parallel}$ pushes along the…

Elastic & inelastic collisions

‘Jumping on a trampoline’ and ‘jumping on asphalt’ are of course two very different feelings. The “impact” with the surface is very different. In one…

Rotational stability & gyroscope

The phenomenon of precession explains why a spinning top keeps spinning, and even why a tilted spinning top keeps that same tilt (while rotating –…

Angular momentum conservation

Just like we have a linear momentum conservation law telling us how the sum of all momentum never changes (the same before and after any…