Introduction
Dive into the fascinating world of Earth’s rotation and its impacts on our daily lives. From the Law of Inertia to the subtle changes in our planet’s rotation, we’ll explore it all.
The Law of Inertia
As planet Earth rotates at a constant speed of 1,675 km/h, we’ve been rotating with it for millions of years. This motion is akin to a plane in mid-flight – we’re not pushed to the bottom of the plane because we move at the same speed as the vehicle. During takeoff and landing, we feel forces pushing us back and forth, as our speed relative to the aircraft changes. Similarly, if the Earth were to suddenly stop spinning, we would all be propelled away due to our inertia.
– Frank William, Weirdworld
Earth, Galaxy, and Motion
- It’s not just Earth that spins endlessly. Our entire galaxy, the Milky Way, rotates at about 250 km per second. Despite the staggering numbers, we feel nothing, as we, along with Earth and the rest of the galaxy, share the same speed and direction.
- The centripetal acceleration resulting from Earth’s rotation is 0.03 m/s² at the equator and zero at the poles. We don’t perceive this acceleration because it’s counteracted by gravity, which exerts a force of 9.8 m/s². If our planet were a perfectly spherical object with uniform gravity, we’d weigh 0.3% less at the equator than at the poles.
- Each day, the rotational speed of Earth experiences a minute decrease, lengthening the duration of a complete revolution. Consequently, each «day» becomes roughly two thousandths of a second longer. Although this change is incredibly subtle, we don’t directly sense it. However, if Earth’s rotation were to suddenly cease, everything on its surface would hurtle away at 465 m/s.
Environmental Impact
Earth’s rotation significantly influences sea currents and weather patterns. The Coriolis inertial force causes air masses to follow curved paths instead of straight lines across the globe. This swirling motion creates the cyclones and hurricanes that evoke our apprehension.
Reader’s Inquiry
Reader’s question: Ariane S. Garriado, Santo André, SP
Sources
- Science Alert
- Mental Floss
- University of California
- EarthSky
- Cool Cosmos