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If the earth is round, why dont we fall off it?

Like I get gravity but like when we jump we go upwards, so why if we are on the underneath of the earth don't we fall of it?

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Reply 1

alexharker

gravity doesnt go "down" per se, it acts towards the centre of an object - so if you jump up in australia, youll be pulled back to the centre of the earth by its gravitational force. because we are so small and the earth is so big, that feels like going up and down, rather than going away from the centre of the earth and back towards it (which is what is really happening). hope this helps :-)

Reply 2

Plagioclase

Original post by therealBen

Like I get gravity

Nope I don't think you do, because that's the answer.

Reply 3

miralles.b

Original post by Plagioclase

Nope I don't think you do, because that's the answer.

Bros on smoke, i agree tho you are a bit thick ben

Reply 4

therealBen

Original post by alexharker

omggggg. tysm that makes sense!

Reply 5

therealBen

Original post by miralles.b

Bros on smoke, i agree tho you are a bit thick ben

Ummm exsqueeze me, I shall not let this slide b miralles.

Reply 6

miralles.b

Original post by therealBen

Ummm exsqueeze me, I shall not let this slide b miralles.

I have 14 of your English Alevels, I'm sorry but you are certainly not in a position to let things slide or not, most notably you don't have enough knowledge of how gravity works to model things sliding.

Reply 7

therealBen

Original post by miralles.b

I can already tell you are the type of person to make willy jokes in oxbridge interviews. DHMU!!!

Reply 8

justlearning1469

Original post by therealBen

Like I get gravity but like when we jump we go upwards, so why if we are on the underneath of the earth don't we fall of it?

It means you don't get it.

Gravity pulls towards the center of an object. Your "upwards" is literally going away from the center of the Earth. It isn't actually upwards.

Reply 9

therealBen

Original post by justlearning1469

It means you don't get it.

Gravity pulls towards the center of an object. Your "upwards" is literally going away from the center of the Earth. It isn't actually upwards.

Then why aren't we pulled to the centre of the universe? and hence falling off the earth!!!

Reply 10

miralles.b

Original post by therealBen

I can already tell you are the type of person to make willy jokes in oxbridge interviews. DHMU!!!

At least I'd get an oxbridge interview and have a basic understanding of the world around me, you wouldn't even have the opportunity to make a willy joke xx

Reply 11

DarylO

Because for every action, there is an equal and opposite reaction. When we jump, we create a force that the force of gravity matches in the opposite direction. We cannot create enough of a force to create a reaction that will propel us through the earth's crust and into its core.

Reply 12

therealBen

Original post by miralles.b

At least I'd get an oxbridge interview and have a basic understanding of the world around me, you wouldn't even have the opportunity to make a willy joke xx

omg so rude!

Reply 13

justlearning1469

Original post by therealBen

Then why aren't we pulled to the centre of the universe? and hence falling off the earth!!!

Sure, the supermassive black hole has a huge amount of gravity. But it is so far away from Earth, the gravity from it can be considered negligible to us humans, in most cases.

Meanwhile the Earth is very close to us.

(edited 1 year ago)

Reply 14

DarylO

What's wrong with willy jokes at an interview? They need to know the real you ^_^

Reply 15

miralles.b

Original post by DarylO

What's wrong with willy jokes at an interview? They need to know the real you ^_^

Exactly, I actually got a place even though I told them I had a 3 inch behemoth xx

Reply 16

DarylO

Original post by miralles.b

Exactly, I actually got a place even though I told them I had a 3 inch behemoth xx

Lmaooo. They had no choice but to accept you after hearing that :u:

Reply 17

bl0bf1sh

Original post by therealBen

Like I get gravity but like when we jump we go upwards, so why if we are on the underneath of the earth don't we fall of it?

People "Down Under" have sticky shoes, from walking on all the sticky spider silk, which is why there are so many spiders in Australia.

Reply 18

Rufus The Red

Original post by therealBen

Then why aren't we pulled to the centre of the universe? and hence falling off the earth!!!

There are a few reasons I can provide. Two of them are due to the way gravitational attraction works and the other one is that the question doesn't really work.The ratio of the square of an object's orbital period with the cube of the semi-major axis of its orbit is the same for all objects orbiting the same primary.
(I apologise to any physicists, I think this is right-ish).

Every object is attracted to every other object, but this varies based both on the masses of the two objects and the reciprocal of the distance between them. Specifically, it varies based on the inverse distance squared, i.e doubling the distance between two objects quarters the force of attraction. Therefore, given how much closer we are to the earth than any larger mass the force between us and the earth is great enough that we neither fall off nor can we notice the difference in force.

Objects may be pulled towards something and accelarate towards them (note that acceleration is a vector rather than a scalar so the speed of an object may not be changing, but rather the direction), however if they are in a perfect orbit the distance will remain constant despite the force and changing acceleration.
This is why the moon is not moving towards the earth (it's actually moving away gradually), and why the earth doesn't fall into the sun or the solar system into the centre of the galaxy.

In terms of your question, the universe doesn't have a centre per se. At the beginning of the universe, all matter was (we assume) concentrated in an infinitely small point, this then expanded out to form the universe, but since everything was at the centre, technically everywhere is now the centre. The speed of light means that we can look towards the oldest part of the universe and that may seem like the centre, but observing from that point we would seem similarly old and could be reasonably assumed to be the centre.

Consider this: there is a sphere on which two dimensional people live, they may move freely along the surface, there is no edge to it for them to reach, but they have no conception of any third dimension beyond their plane of existance. Where is the centre?
As a three dimensional person we can tell that the centre is in the middle of the sphere, but the two dimensional people can't tell that this surface is a three dimensional shape as they are limited to observing in only two dimensions.
Raising all the dimensions by one gives us the scenario which we find. We cannot intuitively observe a four dimensional sphere and tell that we are on its surface (or rather the equivalent next dimensional thing), so we are not able to tell where the surface is.

(Dark matter and dark energy are also doing funky things with matter and the expansion of the universe).

Reply 19

artful_lounger

Universities Forum Helper

It's because they cut corners when building the universe and hired a non-union crew and they didn't switch the universal down direction on, so now no matter what our orientation is we have to be pulled towards the nearest massive object forever like idiots. If only they hired a union crew!