The Earth keeps spinning.

It’s spinning non-stop even at this moment.

But we don’t feel the Earth spinning.

Is it because it’s slow?

The Earth rotates around the equator at a rate of 463 meters per second.

At a speed of 463 meters per second

The speed is 1667 km/h.

It’s incredibly fast.

But why can’t we feel the Earth’s rotation speed, which is spinning so fast?

Here’s why:

The centrifugal force we feel must be thought of in circular motion.

But 463 meters is the speed when going in a straight line.

Let’s consider the speed in circular motion, that is, the angular velocity.

The angular velocity of a 360 degree rotation in 24 hours is

360÷24÷3600 seconds.

This gives about 0.004 degrees.

That is, we rotate 0.004 degrees per second.

10 seconds is 0.04 degrees, 100 seconds is only 0.4 degrees.

It is a subtle angle that is very difficult for a person to feel.

For the acceleration we feel, the velocity must change in a linear motion.

In circular motion, the direction always changes, so even if the speed is constant, when the direction changes, you always feel the acceleration.

But the Earth’s rotation changes direction only by 0.004 degrees per second.

In fact, it’s almost like running in a straight line at a constant speed of 463 meters per second.

That is, it is very difficult to feel the acceleration.

therefore. Our body does not feel the acceleration caused by the Earth’s rotation.

Let’s look at it more quantitatively. The centrifugal force felt by an object of mass 1 due to the rotation of the Earth is

At F=ma, in circular motion a is r*(w squared), w=v/r, so the centrifugal force F=m*(v squared)/r.

If you do the math, you get about 0.034 metric per sec squared at the equator.

Earth’s gravitational force is 9.8 meters square, and the centrifugal force is dust compared to gravity.

So, although we receive centrifugal force due to the rotation of the Earth, the gravity of the Earth holds us firmly.

For this reason, we do not feel that the Earth rotates quickly.

Of course, someone who majored in biology in addition to this said. The cochlea in the course of human evolution

It is said that they do not feel it because they have already adapted to the rotation of the Earth.

A rotation we cannot feel!

But thanks to the rotation we can live! Don’t forget!