...I'm just happy building the stock kit and tuning for minimum smoke.
I'll be soldering right along with you. I ordered the four-digit clock yesterday when I read your thread. Ordered the six-digit clock today when I read Betz' post. Contrary to popular opinion, you can buy time. You can also manufacture time. Thanks to the Chinese, you can afford your very own Capt. Hook timepiece collection.
What to do with so many clocks? Plot the Freq vs Temp for each crystal and then put them in an insulated box where they'll be maintained at a turning point.
(A thermistor, light bulb, and 8-pin PIC keep the foam box at the set point. A propeller, the 1pps output of a GPS module, and a cold day, produce the s-curve data.)
DOH! Even cheaper! Advertised at $1.78, which actually rings up to $1.85 after the Paypal currency exchange. It's ALWAYS more. Is Elon pocketing the difference?
It's ALWAYS more. Is Elon pocketing the difference?
I don't think Elon Musk has had any ownership in PayPal since he and the other founders sold it to eBay, though he later did buy back the x dot com domain for both obvious and "sentimental" reasons. If anything he'd be just a regular shareholder.
That said, buy enough solar panels from him and one Tesla roadster, and he'll send you out into space in it. "To not-quite-infinity, and beyond!"
(This is from Musk's Twitter page. He spelled aphelion from the full prefix "apo," as in apogee or apoapsis. Must be what they teach at UPenn!)
Is it already on this trajectory? Every time I look at the video feed it looks like it's in the same high earth orbit.
Either it will slowly distance itself from earth, or the separation will occur at a later date?
The Roadster and its mount are no longer streaming video or orbiting Earth. Live video streamed only for about four hours on the day of the launch. At hour six, the second stage was restarted and burned until propellant was exhausted. The car and the spent second stage have been in an elliptical orbit about the Sun ever since.
Is it already on this trajectory? Every time I look at the video feed it looks like it's in the same high earth orbit.
It's still pretty close to us, and after its final burn would be in this orbit to stay (until some gravitation pull nudges it away). The trajectory shows the car isn't going to hit Mars or even zip by it (not on the first try, anyway), and other aspects of the final orbit shows a Mars flyby/impact may have been just a rumor.
I found it interesting that when the car comes around to the sun, at perihelion it will be traveling at over 75,000 miles per hour. That's pretty good for an electric car!
Most of that speed it got from the Earth which travels around the Sun at about 67,000 miles per hour. So that particular Tesla will only be going (at its fastest) about 8,000 mph faster than other cars on Earth - and most of the time when it's closer to aphelion, it will be going slower than all the other earthbound cars!
Galilean relativity (plus Einstein hisself) says such speed is relative. An observer on gravitation body A cannot determine his speed. Only an observer wholly outside body A, who has a different reference point, can do that. We certainly do not experience our 1000 MPH velocity on the surface of the earth, nor do accelerometers, gyros, and other earth-bound instruments measure it. Newtonian mechanics doesn't allow it.
Elon's Roadster is a self-defined gravitational body with itself as an inertial frame of reference. Its speed is defined by its orbit around the sun, while my Toyota's speed is defined by how fast its old tires will spin over the earth. Sadly, I don't get to combine the relative speeds of my van, the earth's rotation, its orbit about the sun, the sun's orbit around the Milky Way, the Milky Way's speed through space (about 1.4 million MPH), and so on.
Hmm...Sure an observer on a gravitational body can determine his speed. Or at least, a speed.
If I happen to know the masses of the Earth and myself then I know how much force due to gravity I should be exerting on the ground. If I measure that force, with sufficiently accurate bathroom scales, and it turns out to be less that I think it should be, then something is up. Either the Earth is accelerating away from me or, more likely, it is rotating and my weight is being reduced by the resultant centripetal force. Given I know the diameter of the Earth I can now calculate my orbital speed.
Gyros measure the rate of rotation, not speed. You can only infer your speed using further calculation, which is not the same thing as taking a direct measurement.
As far as I know, the thought experiment of Galileo's ship still holds true, and unaccelerated motion is relative.
You can only infer your speed using further calculation, which is not the same thing as taking a direct measurement.
I'm not sure why that makes any difference. There are plenty of things we measure everyday via some indirect calculation. For example when measuring resistance with your DVM. Besides, surely a measurement of speed is always indirect, speed = distance / time, that is two things to measure and a calculation.
Your statement was that "An observer on gravitation body A cannot determine his speed." I don't interpret the word "determine" there as "direct measurement". Quite the opposite in fact.
Let's try a different technique to determine our orbital velocity around the Earth's center. Look at distant galaxy low on the horizon to the east, and measure it's red shift. That gives you an estimate of how fast it is receding from you. Then measure the redshift of the same galaxy when it is low in the sky to the west. You will measure a different velocity. The difference between the two measurements will be you orbital velocity around the center of the Earth. Perhaps an even more direct measurement than the gyro thing.
Admittedly we may not be able to resolve the tiny difference in redshift here but in principle it would work.
As far as I know, the thought experiment of Galileo's ship still holds true, and unaccelerated motion is relative.
Any motion is relative to some other object or you do not have any way to measure it.
Quite so.
It's worse than that. Without a reference you cannot even define movement or velocity.
For my proposed measurements above, of our velocity as we orbit the Earth's center, I am choosing the far away galaxies, the whole observable universe in fact, as my reference frame.
If I happen to know the masses of the Earth and myself then I know how much force due to gravity I should be exerting on the ground. If I measure that force, with sufficiently accurate bathroom scales, and it turns out to be less that I think it should be, then something is up. Either the Earth is accelerating away from me or, more likely, it is rotating and my weight is being reduced by the resultant centripetal force. Given I know the diameter of the Earth I can now calculate my orbital speed.
Same here. And I always used to eat bucket loads. Annoying isn't?
Old farts grumbling. Grumble, grumble...
About that metal detector above, anyone think it could be modified to detect the presence of 50 to 200KHz signals from various bits of apparatus from half a meter away? I have an odd requirement to do such a thing.
GordonMcComb,
Your statement was that "An observer on gravitation body A cannot determine his speed." I don't interpret the word "determine" there as "direct measurement". Quite the opposite in fact.
In the context of my post I would have thought it was obvious I was talking about reference frames (Galileo etc.), but you're right that I wasn't specific in laying out the exact conditional statement. You talk about determining speed using an external reference, but that's not the relevant issue. We can always judge our speed by counting telephone poles out the train window, but inside the train, shutters closed, we're not moving.
The point is we live in a relativistic world. It doesn't matter we're hurtling through space at 1.4 million MPH hitching a ride on a galaxy. I'm not moving an inch sitting in my chair typing this.
Forgive my confusion. The context in my mind was that Tesla mentioned above shot into orbit around the Sun.
What reference should we use in that case?
We can always judge our speed by counting telephone poles out the train window, but inside the train, shutters closed, we're not moving....The point is we live in a relativistic world. It doesn't matter we're hurtling through space at 1.4 million MPH hitching a ride on a galaxy. I'm not moving an inch sitting in my chair typing this.
Well, almost. As we see, with a gyro or Foucault Pendulum, you could observe that you are rotating. Even without looking outside of the room you are in.
Thing is, we don't live in an inertial reference frame. The thing we live on rotates.
I'm happy with Galileo and even Special Relativity. I lost the thread when it came to General Relativity back in Uni. though.
I did take a break and build the clock. Quick & fun solder job, 20 minutes max. Worked first time, I soldered a USB cable to it for power. Only gotcha is 24 hour time only. Has 2 alarms and chime function. Daddy like!
Watch orientation of the resistor bank. There's a common ground marked by a dot on the part, just match that to the PCB dot. Outer power contact is positive. If you need help, see http://www.instructables.com/id/C51-4-Bit-Clock/
Comments
https://www.ebay.com/itm/Top-Metal-Detector-Kit-Electronic-Kit-DC-3V-5V-60mm-Non-contact-Sensor-DIY-Kit/322928180444
Absolutely. You can tell its working when the time display disappears
https://ebay.com/itm/Digital-C51-6-Bits-Electronic-Clock-Electronic-Production-Suite-DIY-Kits/332064620488?hash=item4d5097ffc8:g:ZOkAAOSw2xRYVGCS
Ordered 2 for the grandkids
Link out the regulator and use USB power
What to do with so many clocks? Plot the Freq vs Temp for each crystal and then put them in an insulated box where they'll be maintained at a turning point.
(A thermistor, light bulb, and 8-pin PIC keep the foam box at the set point. A propeller, the 1pps output of a GPS module, and a cold day, produce the s-curve data.)
... walk into a bar. The light bulb turns (on) to the ...
https://www.ebay.com/itm/4-Bits-Digital-AT89C2051-Electronic-Clock-Production-Suit-Set-DIY-Kit-BBC/142665472243
I don't think Elon Musk has had any ownership in PayPal since he and the other founders sold it to eBay, though he later did buy back the x dot com domain for both obvious and "sentimental" reasons. If anything he'd be just a regular shareholder.
That said, buy enough solar panels from him and one Tesla roadster, and he'll send you out into space in it. "To not-quite-infinity, and beyond!"
(This is from Musk's Twitter page. He spelled aphelion from the full prefix "apo," as in apogee or apoapsis. Must be what they teach at UPenn!)
Either it will slowly distance itself from earth, or the separation will occur at a later date?
The Roadster and its mount are no longer streaming video or orbiting Earth. Live video streamed only for about four hours on the day of the launch. At hour six, the second stage was restarted and burned until propellant was exhausted. The car and the spent second stage have been in an elliptical orbit about the Sun ever since.
It's still pretty close to us, and after its final burn would be in this orbit to stay (until some gravitation pull nudges it away). The trajectory shows the car isn't going to hit Mars or even zip by it (not on the first try, anyway), and other aspects of the final orbit shows a Mars flyby/impact may have been just a rumor.
I found it interesting that when the car comes around to the sun, at perihelion it will be traveling at over 75,000 miles per hour. That's pretty good for an electric car!
Elon's Roadster is a self-defined gravitational body with itself as an inertial frame of reference. Its speed is defined by its orbit around the sun, while my Toyota's speed is defined by how fast its old tires will spin over the earth. Sadly, I don't get to combine the relative speeds of my van, the earth's rotation, its orbit about the sun, the sun's orbit around the Milky Way, the Milky Way's speed through space (about 1.4 million MPH), and so on.
If I happen to know the masses of the Earth and myself then I know how much force due to gravity I should be exerting on the ground. If I measure that force, with sufficiently accurate bathroom scales, and it turns out to be less that I think it should be, then something is up. Either the Earth is accelerating away from me or, more likely, it is rotating and my weight is being reduced by the resultant centripetal force. Given I know the diameter of the Earth I can now calculate my orbital speed.
Sure gyros experience the rate of rotation of the Earth. Newton does not forbid that:
http://www.tkt.cs.tut.fi/research/nappo_files/Symposium_Gyro_Technology_2010_web.pdf
Again, with that gyro measurement of the Earth's rotational speed and knowing the diameter of the Earth I can calculate my orbital velocity.
Of course Foucault was effectively doing that with his pendulum in 1800 and whatever.
As far as I know, the thought experiment of Galileo's ship still holds true, and unaccelerated motion is relative.
Same goes for speed. Speed to the ground, Airspeed, whatever, you need a reference point, as speed is relative to the observer.
Maybe the clue to FTL is that it is not observable...
Mike
Your statement was that "An observer on gravitation body A cannot determine his speed." I don't interpret the word "determine" there as "direct measurement". Quite the opposite in fact.
Let's try a different technique to determine our orbital velocity around the Earth's center. Look at distant galaxy low on the horizon to the east, and measure it's red shift. That gives you an estimate of how fast it is receding from you. Then measure the redshift of the same galaxy when it is low in the sky to the west. You will measure a different velocity. The difference between the two measurements will be you orbital velocity around the center of the Earth. Perhaps an even more direct measurement than the gyro thing.
Admittedly we may not be able to resolve the tiny difference in redshift here but in principle it would work. Nothing I have said contradicts good old Galileo.
It's worse than that. Without a reference you cannot even define movement or velocity.
For my proposed measurements above, of our velocity as we orbit the Earth's center, I am choosing the far away galaxies, the whole observable universe in fact, as my reference frame.
I think that is fair enough.
When I talk of my mass above I don't mean me actually. I mean one standard Heater mass calibrated at NIST.
At least I started out being underweight till I got to 55.
Old farts grumbling. Grumble, grumble...
About that metal detector above, anyone think it could be modified to detect the presence of 50 to 200KHz signals from various bits of apparatus from half a meter away? I have an odd requirement to do such a thing.
In the context of my post I would have thought it was obvious I was talking about reference frames (Galileo etc.), but you're right that I wasn't specific in laying out the exact conditional statement. You talk about determining speed using an external reference, but that's not the relevant issue. We can always judge our speed by counting telephone poles out the train window, but inside the train, shutters closed, we're not moving.
The point is we live in a relativistic world. It doesn't matter we're hurtling through space at 1.4 million MPH hitching a ride on a galaxy. I'm not moving an inch sitting in my chair typing this.
What reference should we use in that case? Well, almost. As we see, with a gyro or Foucault Pendulum, you could observe that you are rotating. Even without looking outside of the room you are in.
Thing is, we don't live in an inertial reference frame. The thing we live on rotates.
I'm happy with Galileo and even Special Relativity. I lost the thread when it came to General Relativity back in Uni. though.
If only I had some time to build!
Like "Amazon Yesterday Shipping"
But with interesting stuff...
Watch orientation of the resistor bank. There's a common ground marked by a dot on the part, just match that to the PCB dot. Outer power contact is positive. If you need help, see http://www.instructables.com/id/C51-4-Bit-Clock/