Flywheels store rotational kinetic energy ($KE = \frac{1}{2}I\omega^2$). A large $I$ (achieved by putting mass at the rim, like a ring) means more energy stored per unit angular velocity. Industrial flywheels in engines maintain steady rotation despite intermittent torque pulses. Their high $K^2/R^2$ (ring ≈ 1) is desirable for energy storage, but the same property makes them slow to accelerate — the trade-off exploited in rolling race physics.

Gyroscopes and Spinning Tops utilise conservation of angular momentum to maintain orientation. A spinning gyroscope resists changes to its axis of rotation ($\vec{L}$ resists change when $\tau_{ext} \approx 0$). This principle underlies inertial navigation systems in aircraft, submarines, and spacecraft, and the self-stabilising behaviour of a spinning bicycle wheel.

Figure Skating and Diving demonstrate angular momentum conservation in sport. A diver tucking from a stretched layout reduces $I$, increasing $\omega$ to complete multiple somersaults. A figure skater pulling arms in to spin faster ($I$ decreases, $\omega$ increases). The energy increase comes from muscular work done against centrifugal tendency.

Automotive Differentials allow the two rear wheels of a car to rotate at different speeds during cornering. Without it, the outer wheel (which must cover a longer arc) would slip. The differential exploits rotational kinematics to distribute torque while permitting unequal angular velocities.

Ball Bearings reduce friction in rotating machinery by converting sliding friction to rolling friction. Since rolling without slipping has zero contact-point velocity, the energy dissipation mechanism changes fundamentally — rolling friction is far smaller than kinetic friction, enabling high-speed rotation with minimal heat generation.

Earthquake-Resistant Building Design uses moment of inertia concepts: rotating structures (seismic isolators, tuned mass dampers) are designed with specific $I$ values to have resonant frequencies away from typical earthquake frequencies, protecting the building.

Sports Balls and Spin — a cricket ball bowled with backspin (topspin) curves differently because the rotational KE modifies the effective translational velocity at the contact point, altering friction direction and hence trajectory — directly applying $v_{contact} = v_{cm} \pm \omega R$.