A few Questions about Earths Orbital Speed Around the Sun.

[TheCuriousMind]

Disclaimer: I am, not a physicist nor do I possess any knowledge or understanding of the math involved behind the answers to these questions, but I still want to learn

 

On Earth, we’re fairly close to the Sun, at a distance of some 150 million km (93 million miles). Earth's orbit around the Sun takes 940 million km and 365.24 days, or what we call one year. Over this time, Earth notches up a speed of 108,000km/h (67,000 mph) on its journey round the Sun. <-- Thats impressive! 

Let's talk about Gravity for a sec, or at least a simple form of it, outside of GR, and its effect on us. 

Gravity is not the only source of g-forces.

A living being Like you or I, whenever in a vehicle, like a car or a plane, are traveling X/Speed and we suddenly change the vehicles velocity, speed up, slow down, or make a turn, your velocity will change.

The faster this happens, the more G-force you will experience. In some instances, these effects are extreme enough to cause the driver/piolet/passenger to lose consciousness or pass out.

For my next few questions, I'd like to imagine the earth like a vehicle that is carrying passengers equal to the total population of earths Living Beings.

Question Number one: If the Earths Orbital Speed around our sun were to suddenly Double in speed, would we feel any extreme G force from this? If not, would question number 2 hold somewhat of the answer to why. 

Question Number two:  Does earths massive size, in comparison to a smaller vehicle such as a jet/plane, play a role in why we don't feel the same effects of G-force at these speeds being on earth like we would if we were traveling at these speeds in a much smaller vehicle. 

 

I know I have very little understanding of these concepts that's why I am asking. 

And I hope this was coherant enough to understand my questions  

If not please feel free to ask me to elaborate more, and I will do my best to. 

 

Edited February 16, 2023 by TheCuriousMind
Small Typo oops

[Lorentz Jr]

1 hour ago, TheCuriousMind said:

Gravity is not the only source of g-forces.

Actually, gravity doesn't create g-forces at all. None that can be felt, anyway. What we experience as the "force of gravity" is really the pressure force of the floor or whatever other object is supporting us.

1 hour ago, TheCuriousMind said:

Question Number one: If the Earths Orbital Speed around our sun were to suddenly Double in speed, would we feel any extreme G force from this?

Taking the word "suddenly" literally, we would all be killed by the infinite force required to accelerate us instantaneously. Even a sharp gravitational pulse would rip us and Earth apart by accelerating some parts more than others.

1 hour ago, TheCuriousMind said:

Question Number two:  Does earths massive size, in comparison to a smaller vehicle such as a jet/plane, play a role in why we don't feel the same effects of G-force at these speeds being on earth like we would if we were traveling at these speeds in a much smaller vehicle.

I'll assume you're asking why we don't feel the centripetal force of orbiting the sun at high speed. Speed itself doesn't require any force as long as it's constant and the motion is in a straight line.

In Newtonian physics (i.e. old-fashioned Physics 101), the reason we don't directly feel the effects of gravity is that inertial mass is equal to gravitational mass. Inertial mass is the m in Isaac Newton's 2nd law, [math]F=ma[/math], and gravitational mass is the mass in his law of gravity, [math]\displaystyle{F_g = \frac{GmM}{r^2}}[/math]. They cancel out: If gravity is the only force acting on an object, then [math]\displaystyle{ma = \frac{GmM}{r^2}}[/math], so the object's acceleration is [math]\displaystyle{a = \frac{GM}{r^2}}[/math]. Gravity affects every molecule in your body exactly the same way, so your nerves don't sense any change in your body's configuration.

This is why Albert Einstein was able to model gravity as the curvature of spacetime in his general theory of relativity. In that theory, gravity isn't even a force. It's just the curvature of spacetime, and objects with no (other) forces on them simply travel along "straight" lines. Not literally straight lines, because space itself is curved, but along curves called "geodesics", which are as straight as any path can be in the curved space.

Edited February 16, 2023 by Lorentz Jr

[StringJunky]

Mass-energy curves spacetime, which causes freefall in objects in free space. Force of gravity is the resistance one feels when our own curved freefall path (geodesic) is inhibited by a more massive object we are attached to i.e. Earth. Spacetime is the 3 dimensions plus time. It is a  mathematically-described geometric platform with spatial and temporal co-ordinates scientists  use to describe and track events* in space and time. 

*From Wiki: In physics, and in particular relativity, an event is the instantaneous physical situation or occurrence associated with a point in spacetime (that is, a specific place and time). For example, a glass breaking on the floor is an event; it occurs at a unique place and a unique time.

Edited February 16, 2023 by StringJunky

[TheCuriousMind]

Quote

I'll assume you're asking why we don't feel the centripetal force of orbiting the sun at high speed. Speed itself doesn't require any force as long as it's constant and the motion is in a straight line.

In Newtonian physics (i.e. old-fashioned Physics 101), the reason we don't directly feel the effects of gravity is that inertial mass is equal to gravitational mass. Inertial mass is the m in Isaac Newton's 2nd law, F=ma, and gravitational mass is the mass in his law of gravity, Fg=GmMr2. They cancel out: If gravity is the only force acting on an object, then ma=GmMr2, so the object's acceleration is a=GMr2. Gravity affects every molecule in your body exactly the same way, so your nerves don't sense any change in your body's configuration.

This is why Albert Einstein was able to model gravity as the curvature of spacetime in his general theory of relativity. In that theory, gravity isn't even a force. It's just the curvature of spacetime, and objects with no (other) forces on them simply travel along "straight" lines. Not literally straight lines, because space itself is curved, but along curves called "geodesics", which are as straight as any path can be in the curved space.

Quote

Mass-energy curves spacetime, which causes freefall in objects in free space. Force of gravity is the resistance one feels when our own curved freefall path (geodesic) is inhibited by a more massive object we are attached to i.e. Earth. Spacetime is the 3 dimensions plus time. It is a  mathematically-described geometric platform with spatial and temporal co-ordinates scientists  use to describe and track events* in space and time. 

*From Wiki: In physics, and in particular relativity, an event is the instantaneous physical situation or occurrence associated with a point in spacetime (that is, a specific place and time). For example, a glass breaking on the floor is an event; it occurs at a unique place and a unique time.

I want to start off with saying thank you for your responses! 

I want to understand this as much as possible, so here is how I tried to understand it myself. Correct me if I am wrong. 

So, we are essentially traveling through Space-time in a straight line? But our path is curved due to the curvature of spacetime, caused by (The Sun) In this example. 

And gravity is a consequence caused by this Curvature?

We are falling towards the sun, but we keep missing it due to the speed the earth is traveling. 

Does this explain gravity in space, things are actually just free falling? And not weightless as most assume? 

[StringJunky]

49 minutes ago, TheCuriousMind said:

I want to start off with saying thank you for your responses! 

I want to understand this as much as possible, so here is how I tried to understand it myself. Correct me if I am wrong. 

So, we are essentially traveling through Space-time in a straight line? But our path is curved due to the curvature of spacetime, caused by (The Sun) In this example. 

And gravity is a consequence caused by this Curvature?

We are falling towards the sun, but we keep missing it due to the speed the earth is traveling. 

Does this explain gravity in space, things are actually just free falling? And not weightless as most assume? 

Yes, when there is no other influence, things are in freefall. Freefall is a curvilinear motion (geodesic), with the degree of curvature dictated by the mass-energy of the larger object. The two attracted objects actually affect each other but it's simpler that way. If you are freefalling you feel no acceleration i.e. no change in speed or direction... that's gravity. If either of those changes, speed or direction - which we call velocity because it has those two components - you are no longer under freefall and one experiences a resistance in ourpath of motion. That's when we think we feel gravity.

Edited February 16, 2023 by StringJunky

[TheCuriousMind]

14 minutes ago, StringJunky said:

Yes, when there is no other influence, things are in freefall. Freefall is a curvilinear motion (geodesic), with the degree of curvature dictated by the mass-energy of the larger object. The two attracted objects actually affect each other but it's simpler that way. If you are freefalling you feel no acceleration i.e. no change in speed or direction... that's gravity. If either of those changes, speed or direction - which we call velocity because it has those two components - you are no longer under freefall and one experiences a resistance in ourpath of motion. That's when we think we feel gravity.

Thank you!

I feel a bit better about this now, I have a very small grasp on things, Welp off to the library I go tomorrow  Gunna take a look into some physics books, any recommendations for a beginner curious to learn? 

[studiot]

2 hours ago, TheCuriousMind said:

Thank you!

I feel a bit better about this now, I have a very small grasp on things, Welp off to the library I go tomorrow  Gunna take a look into some physics books, any recommendations for a beginner curious to learn? 

 

Difficult to answer without knowing where you are or what your level of maths is.

Note that some 'modern physics'  books assume you know classical physics quite well so are best avoided unless you have this grounding.

Some deserve the title/description Physics for the Modern World instead. I will only mention this type.

Some good american authors are

 

Arthur Beiser

He has written several versions  - try for Concepts of Modern Physics.

 

Robert Mills

An introduction to Contemporary Physics

Exactly what it says on the tin. An introduction with lots of background explanation/ information. Mills has an exceptionally clear way with words.

 

Leonard Susskind and Art Friedman

Offer a three volume set in Penguin with the aim of 'The minimum you need to know for the subject@

Quite a bit harder than the first two. You need better maths for these.

 

UK authors

You will never go wrong with almost any edition of

Nelkon and Parker

Ordinary level Physics

Advance level Physics

If you will be looking at UK stuff you might also like to look at 'Engineering Science'.

UK use to offer more practical, less mathematical,  and wider aspect courses in what amounted to a combination of basic Physics and Materials Science, much of which has been dropped from 'modern physics' courses. They offer a quck and easy way to get many essential facts quickly.