Final answer:
The Law of Conservation of Angular Momentum explains why a tornado spins faster as its radius decreases; it states that in the absence of external torque, the rotational velocity must increase when the object's radius is reduced to conserve angular momentum.
Step-by-step explanation:
The phenomenon of a tornado spinning faster as its radius shrinks is best explained by the Law of Conservation of Angular Momentum. This physical law highlights the relationship between the spin of the object and its radius – when the radius decreases without any external torque acting on the system, the rotational velocity increases to conserve angular momentum. A common analogy is an ice skater who spins faster when pulling her limbs closer to her body, reducing her rotational inertia and subsequently increasing her rotational speed to conserve angular momentum.
Observable in various astronomical phenomena, this effect can be seen when a protostar contracts and spins faster. Similarly, a planet speeds up as it approaches the sun on its elliptical orbit, as described by Kepler's Second Law, which is a natural consequence of angular momentum conservation. Due to the absence of external torques, angular momentum is conserved, and rotational speed increases as the rotational inertia of the system decreases when the radius between the mass and the spin center is reduced.