A World Without Spin!
Imagine waking up one day, and the Earth has suddenly stopped spinning. No sunrise, no sunset—just endless daylight on one side and eternal night on the other. But here’s something even stranger: if you’re standing at the equator, you’d suddenly feel heavier! Sounds bizarre, right? Let’s break it down.
How Rotation Affects Gravity
Gravity is the force that pulls objects toward the center of the Earth. However, because Earth is spinning, there’s an additional force acting on objects—centrifugal force. This force pushes outward and slightly counteracts gravity, making us feel a tiny bit lighter, especially at the equator where the rotational speed is highest (about 1,670 km/h).
The acceleration achieved by any object due to the gravitational force of attraction by any planet is called acceleration due to gravity.
Consider an object of mass “m“ at latitude “l” of the Earth due to the rotation of the Earth, the value of acceleration due to gravity “gl” at a given place is given by gl = g – Rw2 cos2l.where Rw2 cos2l is the component of centrifugal acceleration along the radius of the Earth.
where” r“ is the radius of the circle in which the object is revolving. Here
r = Rcosl
\ gl = g – w2 Rcos2l.
where w is the angular velocity, R is radius of the earth and l is latitude of the place
Right now, the Earth’s rotation creates a slight outward push—called centrifugal force—which reduces gravity at the equator. The equation for gravity at any latitude is:
gl = g – w²R cos²l
This means gravity is highest at the poles (cos 90° = 0) and lowest at the equator (cos 0° = 1). If Earth stops spinning, the centrifugal effect disappears, increasing gravity at the equator by w²R ≈ 0.034 m/s².
| Location | Gravity Calculation | Effect If Earth Stops Spinning |
| Poles (90°) | g (Maximum) | No change |
| Equator (0°) | g – w²R (Minimum) | Increases by w²R (~0.034 m/s²) |
What Happens If Earth Stops Spinning?
If the Earth stops rotating:
- Centrifugal force disappears – The outward push that was counteracting gravity at the equator would be gone.
- Gravity increases at the equator – Without the centrifugal effect, the full force of gravity (9.81 m/s²) would be felt, increasing by about 0.3% (from 9.78 m/s² to 9.81 m/s²).
- Shape of Earth May Change Over Time – Currently, Earth is slightly oblate (bulging at the equator). If rotation stops, gravity would gradually pull the extra mass toward the poles, making the Earth more spherical.
Other Catastrophic Effects
While the increase in gravity is scientifically interesting, the sudden stop of Earth’s spin would cause massive destruction:
- Global mega-tsunamis as oceans redistribute.
- Supersonic winds due to the sudden halt.
- Complete climate shifts affecting ecosystems worldwide.
Summary
While it’s highly unlikely that Earth will ever stop spinning, understanding its effects gives us valuable insight into planetary physics. The increase in gravity at the equator is just one of many profound consequences, proving how interconnected Earth’s rotation is with everything around us.
Name: Sanjay Yadav
Department: Physics JEE (Foundation)
Narayana Jaipur Center (NIHQ)