Earth travelling through space - we can/cannot feel it? (1 Viewer)

[Sanical]

We can’t feel ourselves move through space since we are always at a constant velocity (I think around 100 000km/s) so based on our frame of reference, we can consider ourselves stationary.
However, according to Kepler’s second law, we move faster when the Earth is closer to the sun due to its greater gravitational attraction. If we move faster, that means we would accelerate. If we are accelerating, why can’t we feel it? Wouldn't we feel the reaction force? The acceleration can’t be that insignificant that we cannot feel it?

Help?

 

[jamesfirst]

Wait. If the Earth is orbiting in a circular motion around the sun (or oval... idk), wouldn't it be accelerating due to centripetal force (centripetal acceleration) ?

 

[cheezcake]

It is, but the gravitational acceleration due to the earth far outweighs the negligible acceleration due to centripetal force, so we don't feel it, at least that's a possibility

 

[Sanical]

Ok, what about Earth accelerating when closer to the Sun? Is that also negligible?

 

[Sanical]

Lol, nvm, you guys fail at applying physics =/ Hope for your sakes that nothing above average gets asked.

 

[jamesfirst]

Yeah, because last time I fucking checked, this section didn't relate to the syllabus


no need to be fucking rude, idiot.

 

[Sanical]

Yeah, because last time I fucking checked, this section didn't relate to the syllabus


no need to be fucking rude, idiot.

Hypocrisy and irony at its finest Nice to know that people can't extend their knowledge past the scope of the syllabus.

 

[hayabusaboston]

Hypocrisy and irony at its finest Nice to know that people can't extend their knowledge past the scope of the syllabus.

So what was your problem again? That you don't understand how we can't feel the extra acceleration? In terms of our size on the Earth we need a MASSIVE acceleration before we become conscious of it, consider our speed without acceleration, approx 107,400km/h on average and relate that to the Astronomical Unit (149,598,000 km). The AU is 1400 times bigger. Now that is a HUGE difference, only an absolutely enormous acceleration would be felt by us, because of that difference, which is even small in the solar system, and our own size on Earth. Im not going to guess the acceleration required because I dont know, and everyone has different proprioceptive adaptations which allow them to feel different stimuli at different intensities, so it would be extremely difficult to extrapolate an accurate reading of "vestibular proprioception" for the general population.

 

[hayabusaboston]

Man I recommend you read "A Brief History Of Time" By Stephen Hawking. Very good book and explains a lot if you want to know more about that kind of stuff.

 

[_deloso]

We can’t feel ourselves move through space since we are always at a constant velocity (I think around 100 000km/s) so based on our frame of reference, we can consider ourselves stationary.
However, according to Kepler’s second law, we move faster when the Earth is closer to the sun due to its greater gravitational attraction. If we move faster, that means we would accelerate. If we are accelerating, why can’t we feel it? Wouldn't we feel the reaction force? The acceleration can’t be that insignificant that we cannot feel it?

Help?

It's moving at 30/40 km/s I think. Not 100 000. Anyone who can confirm this?

 

[Sanical]

It's moving at 30/40 km/s I think. Not 100 000. Anyone who can confirm this?

Ah yeah, sorry - it's approx 100 000km/h not km/s

 

[Sanical]

Man I recommend you read "A Brief History Of Time" By Stephen Hawking. Very good book and explains a lot if you want to know more about that kind of stuff.

But this isn't about relativity or anything. I'm simply asking if we can feel the acceleration as we approach the sun. Well, I was bothered to figure it out and the reason we can't feel it is because the acceleration increases gradually, so it can't be felt. And it's also because we accelerate with the Earth as well

 

[hayabusaboston]

So what was your problem again? That you don't understand how we can't feel the extra acceleration? In terms of our size on the Earth we need a MASSIVE acceleration before we become conscious of it, consider our speed without acceleration, approx 107,400km/h on average and relate that to the Astronomical Unit (149,598,000 km). The AU is 1400 times bigger. Now that is a HUGE difference, only an absolutely enormous acceleration would be felt by us, because of that difference, which is even small in the solar system, and our own size on Earth. Im not going to guess the acceleration required because I dont know, and everyone has different proprioceptive adaptations which allow them to feel different stimuli at different intensities, so it would be extremely difficult to extrapolate an accurate reading of "vestibular proprioception" for the general population.

I said km/h

 

[Sanical]

I said km/h

It was reffering to my first post. And yeah, I didn't see that reply but I agree that the acceleration is not large enough for any real difference to occur. The other main reason is that if Earth were to accelerate, we would too since the planets are essentially in free-fall.

 

[romesh]

Maybe they don't teach this clearly enough in HSC, but when it comes to 'feeling' force, you don't feel gravity. The reason, I suppose, is that you don't feel any force along a free-fall trajectory (neglecting friction). The reason you 'feel' weight on Earth is because you are *not* in free fall, you are being stopped by the ground. Thus it wouldn't matter if the gravitational force from the sun was 100x greater and you were falling straight into it, you wouldn't feel it unless something was acting against the resulting gravitational acceleration. Similarly, you don't feel any force in orbit because an orbit is a free-fall trajectory given your orbital velocity.

What you can feel though, is the gravitational gradient from a small, heavy source. That is, if you had a tiny, very massive object, the rate at which the gravitational force changed close to the object would be large. This could lead to a situation where say, your legs had a different gravitational force to your head, and you would definitely notice that.