Why can’t we feel the earth rotating ?

719 views

Why can’t we feel the earth rotating ?

In: Physics

7 Answers

Anonymous 0 Comments

Because it is rotating at a constant rate. You cannot feel speed, only acceleration, and the Earths rotation is not changing and you are not accelerating, so you feel nothing.

Anonymous 0 Comments

Because the centrifugal force from the rotation is quite small and constant for a single location. On the equator where is largest, it is only 0.3% of gravity and on the poles the force it zero. It and the difference in earth radius that change gravity have a measurable effect because the weight differs by 0.5% between the poles and equator.
In any location in between it changes the direction of down slightly.

A human would not feel the difference if your travel between the equator and poles but even a cheap precision scale would detect it.

the centrifugal force is the same as if you drive a car in a circle with 50 meters (164 feet) radius and each lap takes 4 minutes.

So the forces from the rotation is quite a small constant ins strange and direction so it is is like a slight change in gravity.

Anonymous 0 Comments

A carousel takes maybe 6 seconds seconds to complete one rotation, so the centrifugal force pulling you outwards is apparent. The Earth, however, takes 86,400 seconds, so the centrifugal force tugging you away from Earth is negligible compared to the strong gravity pulling you towards the Earth. The force you feel when spinning depends on your *rotational* speed, not your linear speed. Yes, you’re travelling at around 1000mph as you whiz around with the Earth, but because the Earth is so huge, the *rotational* speed is very slow, and only goes around once every 24 hours. So, you feel very, very little centrifugal force.

Anonymous 0 Comments

You’re not sensitive enough to feel it. The centripedal acceleration (the acceleration we feel due to earth’s rotation) varies from basically 0 at the poles to about .034 m/s^2 at the equator. Compared to the normal gravity acceleration of 9.81 m/s%2, the acceleration due to rotation is only about 0.3%. We’re just not that sensitive, especially to constant accelerations.

Electronics can feel it; inertial reference units, like on airplanes or submarines, can detect it and figure out their latitude based on that.

Anonymous 0 Comments

The Earth is very large. So even though it’s rotating at a thousand miles an hour at the equator if you think of it as linear velocity It takes an entire day to go around once.

If you were on a merry-go-round that went around once a day you wouldn’t feel it rotating either.

So it’s very big but it moves at the speed of a clock, and not a normal clock but a 24-hour clock instead of a 12-hour clock.

Technically you weigh ever so slightly less at the equator than you do at the North Pole because of ~~centripetal~~ centrifugal force. but because the Earth is so huge the total angle you change in direction is so tiny that it’s less than a percent difference.

Finally the Earth’s movement is very smooth and continuous. if you’re in an airplane you don’t feel like you’re moving 500 miles an hour because the airplane is moving 500 miles an hour continuously. The car you don’t feel like you’re doing 60 unless you’re turning or going over bumps or something. I mean you do feel it when the car speeds up and slows down but the Earth doesn’t do that.

So the Earth never changes direction, and the Earth never changes velocity, and your sensation of movement is based entirely on changes in direction and velocity

It’s not impossible for an organism to feel these forces in theory, but in practice any organism that evolved to feel the motion of the Earth would go crazy. Such a sense would do you no good.

EDIT: and before the pea dance descend, you on the surface of the Earth undergo a continuous change in velocity as the Earth rotates, abet a tiny and slow one. The earth itself does not undergo a change in velocity. It’s angular momentum is conserved and it’s total velocity as annular consistency.

And for simplicity’s sake I am ignoring the continuous change in direction caused by the motion of the earth around the sun, and the motion of the sun around the galaxy center.

All-motion being relative, some vectors are unimportant in some discussions.

Anonymous 0 Comments

The same reason you can’t feel the speed in a car when you’re holding steady at 60 mph – speed doesn’t create any force that we can feel – acceleration does.

Think of what happens when you get into a car and floor the gas. You’re pushed back into your seat, right? That’s caused by the forces of the rapid acceleration. Hit the brakes hard, and you’ll have the opposite reaction, you’re pushed forward into your seatbelt as speed changes. But if you’re cruising on the highway, at a more-or-less constant speed, you’re not pushed in any direction, you’re sitting normally. You and the car you’re sitting in are both moving at the same speed, without much change. No acceleration, no force.

Same deal with the Earth – it’s rotating constantly, and we’re rotating along with it. Since there’s no change in that speed, we don’t experience any force; we are simply in a constant state of movement through space. If someone could magically “slam the brakes” on the Earth’s rotation, that would cause us to all fly off. But so long as there’s no rapid acceleration or deceleration, there’s no force.

Anonymous 0 Comments

The other answers have gone over the mechanics of why, but there’s another aspect of this: how could you tell?

The earth spins at a constant rate. This gives a centrifugal acceleration, but it’s *always* had that acceleration throughout your entire life. The reason you can tell the motion of a merry-go-round is because you’ve also experienced *not* being on it, so you can tell the difference. But for the rotation of the earth, it’s just ‘normal’.

And *then* there’s the fact that it’s tiny (0.3% of gravity at most) and in roughly the opposite direction of gravity. But while it’s not perceivable with your own senses, there are ways of detecting it like [Foucault’s pendulum](https://en.wikipedia.org/wiki/Foucault_pendulum).