1.) 0.28 g 2.) 15.7 g 3.) 0.0034 g
I assumed 1m radius for the first and 5m for the second, particularly the second sounds off. Anyway… The centripetal force from Earth’s rotation is quiet negligible compared to its gravitation.
The 100 km/h seems a bit much to me, too, but I’m having a hard time finding info on the speed of these…
Considering most people will start to lose consciousness and risk heart issues at like 5g, I’m pretty sure the speed is way off on number 2.
Thus neatly making the case that radius matters.
Girth, you say?
One is but a two pi greater version of the other.
I once lived with a sort of science
skepticistdenier (didn’t believe in the moonlanding nor did he believe that the earth wasn’t flat). He was of the belief that scientists are deceiving the public and one of the examples he gave was that they claim that the earth rotates at 1 670 km/h but if we look outside that’s very clearly not the case and if jump we aren’t flung at that speed to the side. I spent half an hour in a back and forth trying to explain the concept of relative velocity and inertia. It didn’t go anywhere.Edit: changed to denier based on the comment by logos.
Not to be pedantic but I would call them more of a science denier than a skeptic. It’s too close to scientific skepticism which is completely different.
Ask them to jump inside a train
My aunt once mentioned that if the earth wasn’t rotating that we’d all be crushed by gravity, and it’s only the spinning cancelling out that force. I responded by pointing out that gravity is also present at the poles, where you can casually walk faster than the rotation of the earth, and yet no one has been crushed to death there. She responded that it must be something to do with the magnetic fields, and wouldn’t listen to anything I said when I tried to explain the basic concept of angular velocity.
Have him drop a tennis ball in a moving vehicle. It won’t make him understand but you can at least say you tried.
acceleration is the answer
Yes, and a = v^2/r.
Merry-go-round: small radius, big acceleration!
Earth: big radius, small acceleration.
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Lol, guys it’s not acceleration it’s just the exact definition of acceleration. Which is definitely not acceleration.
None of those reference frames are accelerating.
The difference is whether there is a changing velocity or not.
I’m going to assume that you’re defining acceleration in that second statement, because I’m not sure if you are and “changing velocity” is literally what acceleration means. In any case, both acceleration and velocity are vectors, both have a direction, and so a person’s velocity sure as hell can’t be constant when they’re going in circles. Ergo, acceleration. I mean that’s what force is, mass times acceleration, so if you move and you can feel it you’re accelerating. Earth has gravity that can more than cancel it out, but we can’t say the same for rides.
Somebody smarter and with more energy than me can probably come up with a rough estimate of the g’s being pulled in each picture (ignoring gravity).
Edit: looks like someone did!
In any case, both acceleration and velocity are vectors, both have a direction, and so a person’s velocity sure as hell can’t be constant when they’re going in circles.
Well, you can if the space-time is curved right, that’s what orbits are, but that’t just a nitpick.
We do understand the difference between speed and velocity. It’s just that acceleration is the change in velocity over time, not speed.
Rotation is acceleration towards the center with a velocity perpendicular to the centre. Using a frame of reference that rotates along with the object doesn’t change what is physically happening to that object, it just affects the way you observe what’s happening. A rotating frame of reference is itself accelerating and each of those frames of reference are accelerating.
We don’t feel the Earth’s rotation because gravity is accelerating our entire body and surroundings at the same rate, plus it’s not just the spinning keeping us in equilibrium; the left over force holds us on the ground.
The other two feel different because it’s the structures that provide the acceleration towards the centre, which then pushes on our bodies where it makes contact, and then the structure of our bodies pulls the rest and you can feel the forces of things wanting to move in the direction of inertia but being pulled around the circle instead.
If rotating frames of reference weren’t accelerating, turning a car would feel no different from going straight.
It’s almost like there’s no such thing as absolute velocity or something
Relativity
So what would happen if Earth suddenly stopped spinning? Would every building, tree and mountain suddenly fall Eastward?
I believe we’d have worse problems since the atmosphere would still be moving.
Yes, the Earth would be completely spherical in a matter of seconds.
Rather than speed we use radians/degrees per second. One of these things is very small.
If you were only going 6 km/h you were doing it wrong
So true
