71–80 of 125 posts
Is this serious scientific writing? "[...] the gravitational force the Earth exerts on you is canceled out in a freely falling elevator" and "[...] it is impossible to distinguish acceleration from gravity"? Seriously? Isn't acceleration the result of force? Isn't gravity a force? When you are in free fall you accelerate, gravity doesn't "cancel out"!
Anyone know of (or want to give) a clear explanation of how gyros behave? I found the article to be unclear on a number of points. I was also unclear on this: "The first triumph of general relativity was its exact prediction of the orbital precession of Mercury’s perihelion" —does a perihelion precess? I thought it was the planet which was precessing and the perihelion shifted (changing the shape of the planet's orbi…
Earlier quoted context omitted.
Um, I must be missing something here, because feel like I have a pretty simple solution to why there's only a single rotational reference frame, and this is a problem that apparently eluded Einstein , if I'm to believe your link. Imagine a spinning glass ball with a 1cm radius doing one full rotation per second. If we draw a dot on its outer edge, at the end of 1 second that dot will have done a full turn. Given that…
>Rotation is inherently about different particles moving at different velocities. This is why there is an absolute reference frame for it: it is defined by these differences, so by reducing them to zero and making every particle in the ball have the same velocity, we can reach the "absolute". Imagine the ball is floating in space, and you are watching things through a camera fixed to the ball. To you, the two dots wi…
Reading this bought immediately to mind watching Eric Laithwaite's Royal Society Christmas Lecture on the peculiar properties of gyroscopes. It's a shame he apparently pretty much deluded himself, because it was a great lecture https://en.wikipedia.org/wiki/Eric_Laithwaite
Anyone know of (or want to give) a clear explanation of how gyros behave? I found the article to be unclear on a number of points. I was also unclear on this: "The first triumph of general relativity was its exact prediction of the orbital precession of Mercury’s perihelion" —does a perihelion precess? I thought it was the planet which was precessing and the perihelion shifted (changing the shape of the planet's orbi…
Gyros are really simple! Think of the gyro's ring as a series of independent particles flying around really fast in a horizontal circle. Now you push up at one point on that circle. Does the circle move up at that point? No. You're applying a force to each particle only very briefly before it moves past and you're pushing on the next one. But you do impart some upward velocity on the particle during its brief time un…
I think that once you establish that angular momentum is a vector quantity that is entirely consistent with Newton's laws, then the particular case of the gyroscope becomes straightforward.
Earlier quoted context omitted.
Gyros are really simple! Think of the gyro's ring as a series of independent particles flying around really fast in a horizontal circle. Now you push up at one point on that circle. Does the circle move up at that point? No. You're applying a force to each particle only very briefly before it moves past and you're pushing on the next one. But you do impart some upward velocity on the particle during its brief time un…
I think the phrase "...which will continue until the circular path brings it back down" requires a bit more explanation. At this point, you seem to be switching from treating the rotating ring as a stream of independent particles to being a rigid body, but if you treat it as a rigid body from the start, the first part is no longer obvious. I think that once you establish that angular momentum is a vector quantity tha…
You’re totally right that gyroscopes are straightforward if you understand angular velocity as a vector quantity, but it’s not quite so intuitive.