# Homework Help: Flat Earth?

1. Oct 22, 2004

### JimmyRay

How would life on Earth charge if the Earth was a cube instead of a sphere?

...We're suppose make points on how things would change according to newton's laws and stuff...

Well first thing I noticed is that gravity at the Earth's surface wouldnt be constant anymore would it? Because depending on where you are on the Earth, you wouldn't be equal distant from the center then someone else.... What is the center of a cube anyways?

How do I go about answering this question.... I mean we have to apply Newton's laws....But I just dont see it..

2. Oct 22, 2004

### nolachrymose

Well, for one, the revolution pattern of the earth would change, thus changing the life cycles on earth. Also, acceleration due to gravity would have a different value.

Hope that helps you start, and good luck!

Last edited: Oct 22, 2004
3. Oct 22, 2004

### JimmyRay

Yes the Earth's revolution will change, there would be a LOT of changes but... I think I should focus mostly on how Newton's Laws will change?

Acceleration due to gravity would NOT be constant, correct?

4. Oct 22, 2004

### nolachrymose

It's already inconstant, though, depending on where you are you on the earth. This is an interesting question...
Do those three laws extend to things like $F = G\frac{m_1m_2}{d^s}$, or do you mean the basic three laws?

5. Oct 22, 2004

### JimmyRay

It's already inconstant? Isn't it just 9.8 m/s^2 at the Earth's surface, pretty much? .... And those laws, well I guess our teacher wants us to include Universal gravitation and three laws... although it could affect a LOT of things....

I really dont know how to go about answering it though........... hmmm

6. Oct 22, 2004

### nolachrymose

Well, it is usually very close to that value, but it can very based on your position.
I must say, I'm not coming up with anything off the top of my head. I'm studying Universal Gravitation right now, so I'm a bit slower at it. Sorry!

7. Oct 22, 2004

### UrbanXrisis

The earth is not a perfect sphere, it is a little bit smooshed. Your weight at the north pole is less than if you were at the equator. This smooshing is dude to the Earth's spin. As for changes for newtons laws...obviously, at the corners of the cubed earth, there would be less gravatational forces than if you were on the middle face. I think that newtons laws would apply.

8. Oct 30, 2004

### JimmyRay

The only points I can come up with are....

Gravity at the Earth's surface will not be constant
Fn = mg will change
It would also be hard for something to orbit the Earth
Also the Earth will not remain cubic, it will be gradually changing into a sphere because of gravity
Seasons will be different...
The Earth's orbit around the Sun would change.....

I dont know what else to say...

9. Oct 30, 2004

### Parth Dave

The acceleration due to gravity would have a HUGE change depending on where you are. Suppose the distance from the centre of the cube to the closest point is r (the radius of earth), then your acceleration due to gravity is: 9.83 ms^-2. However, if you move to a corner of the earth, your distance changes from 6.37E6 m to 9.01E6 m and thus you acceleration due to gravity would become 4.92 ms^-2. The force of gravity would drastically change from position a to position b on the earth. Your weight would also change enormously as your moved around.

10. Oct 30, 2004

### JimmyRay

Right I said that above didnt I ...

Fn (normal force) = m(mass)g(gravity) would be different?

Yeah you're right as you moved around your weight would be different.