There was a time when I'd glare at anyone who asked me this question with absolute condescension. But I've come to realize that genuinely not everyone knows. Some people don't know why people "At the bottom of the sphere" don't fall off.

Anyway, I'm here to put all doubts to rest, So put on your thinking cap. In All things, Science requires you use your brains at least a little.

So what is really going on here?

The problem.

Imagine a carousel. It's going round and round. the fact is, if you close your eyes, you can feel the carousel spinning. you can CLEARLY feel something happening. the logic then is, why can't we liken the earth to a carousel? after all, it rotates, and at a much faster rate. why? why why why can't we feel the spin? are scientists actually lying to us? is the world not really round and spinning, but instead flat?

Some useful Terms

Before we jump in, We should define some things. these are the things that will help later.

Vectors



You'd be surprised, Vectors actually make all the difference. Vectors are probably one of the most important things in the world. Simply a quantity with Not only Magnitude, But Direction, think of an archer, he's pulling a bow. at that point, the string exerts a force on the arrow. the magnitude of the rope is roughly equal to negative of the distance it is pulled back, and the force is pointed in the direction of the arrow. Did you get that mental picture? it's super important!

Inertial Reference frames.

Don't let the long name scare you. You are simply in an inertial reference frame if and when you are either at rest, or you are moving in a straight line.

The Solution

Alright, So they say the earth is speeding around at 1675km/h. That's pretty fast. if a mattress were to slam against you at that speed, you'd probably die. but you need to realize something, you are also moving at that speed! think about the mattress we said, imagine it's coming for you, and you ran in the opposite direction at that same speed. It wouldn't hurt you. It would just be behind you forever. Exactly like it would be if you weren't moving at all. This is what is known as an inertial reference frame. I'm moving, you're also moving. how are we going to know if we're moving? well, we can't. since we're both in the same inertial frame.

Now, you claim, BUT the earth is not moving in a straight line! It's continuously turning over and over, I should feel the turn!
It is at this point that I point out Vectors.

The force of gravity is a vector that is always pointing towards the center. That force is pulling you towards a center, that center never changes. but you are also moving perpendicularly to that center, so, the force then continues to BEND you around that center, Also, there is a very small, but definite centrifugal force that's trying to get you out, and through the rules of vector addition, they produce a new force, the one you've been experiencing all this while. And it's that force that you feel anytime you jump or do literally anything . . . well, except die.

[img]http://www.ukm.my/rahim/gravity%20lecture%28MSc%29_files/image021.jpg[/img]
Illustrated here

In normal life, we feel turns, this is because when we turn, we feel a NEW force. One that is bending us towards this new direction. Our body quickly realizes that this new force isn't gravity, and decides that it must be because we're turning . . . or something else. For example, When a bus turns, we feel the seat of the bus twisting us along that route AND, most importantly, we feel the air going against our faces. Our brains take the force into context and determines "Hey! we must be turning!"

The Gist

1. As far as we are concerned, we are not moving, because we, the air we breath, and almost every other thing we come in contact with, are in the same inertial reference frame.
2. As far as the universe is concerned, we ARE moving, in a circle, because a force is bending our constant velocity in space around a center.
3. We do not feel any sideways force because there is no force sideways. All the forces acting on us on a normal day are pointing downwards.
4. because we are in an inertial reference frame, everything seems perfectly still.
5. Our brains take a lot of things into context when deciding what force is what. Hence, it can readily differentiate between non-gravity forces.



And that's it!

Thukzee01:
Nice one Teempakguy, still finding it hard y you never went 4 mr nairaland.
I notice it that when a bus tends to turn either left or right in a sharpbend, we happen to go in the opposite direction.
Dunno why ?

This writeup is subject to correction , by my Ogas.
Cc: Teempakguy, Johnnydon.

Teempakguy:
we're simply moving in a straight line, and the bus is turning. The bus turns, our body continues to move in a straight line, by the time our body catches up to what is going on, the bus has already turned and our bodies, which are going in a straight line, hit the side of the bus. It's actually by hitting the bus that we get to turn around. If the bus doesn't have any walls, we would just keep moving in a straight line, and fly out of the bus. Superman style.

Also, I thought the Mr Nairaland was for guys who actually looked good?

hahn:


Ugly people can participate. You have to be proud of your looks. Regardless

Teempakguy:
why compete for something if you don't have a chance of winning

And meanwhile, I don't hold my looks in high esteem. Not as much as hold my intellectual faculties.

Yeah, I'm that typical disheveled absentminded professor

Teempakguy:
why compete for something if you don't have a chance of winning

And meanwhile, I don't hold my looks in high esteem. Not as much as hold my intellectual faculties.

Yeah, I'm that typical disheveled absentminded professor

hahn:
'

Guy bone. You na fine guy na.

From the inside

Dawdy:
Teempakguy, What triggered The Earth's spin?

Thukzee01:

Teempakguy, you are the combination of intellect and charisma.
Ive known you on nairaland for over 2years. Dont let next year pass you by.

ELYMAXiimus:
Well done, Tim. Keep up the good work.
Okay, uhm ... just a few inquiries and contribution:
1) Aren't we moving in the same direction as the earth? The analogy of 'you and the mattrass' got me lost.
If two things move in opposite directions, then definitely there will be a very conspicuous change in position of the two bodies with respect to eachother. Except they move in the same direction and at the same speed.

2) I get the gravity and centrifugal forces action which give a net gravity force. However, I don't get how it explains why we can't discern that the EARTH IS SPINNING. (spinning and revolving -- I hope you aren't mixing up the two?).

3) I think the summary of your discourse of why we cannot feel the earth spinning is that our brain cannot just detect the spinning of the earth. This, to me, is a vague explanation.
Why can't our brain detect that the world we're STANDING ON is spinning/rotating ( and also revolving -- I have an explanation for this, though. )?
Imagine the earth as a ginormous ball, and you're standing on it. And the ball is spinning while going round a fixed circle (just an instance though. We know the earths orbit isn't a circle).
Now, that's the earth's movement.
Let's focus on the spinning effect alone.
How is it possible that our brain can't detect it?

SirWere:
....If gravity is a vector; is there an "upward" gravitational pull An anti-graviton; so to speak

Geofavor:
Gravity is a field. Let's put it this way: if gravitational force is a vector, is there an opposing force to it? As in a PUSH or REPULSION between bodies acting against the pull or attraction between them.

According to newton's third law of motion, there is.

bqlekan:
wow! nice one op..