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Estimation quiz!
08-02-2020, 07:56 AM
Post: #26
RE: Estimation quiz!
(08-01-2020 05:24 PM)ijabbott Wrote:  A useful approximation for electronics: speed of light ≈ 1 foot per nanosecond.
As a continental european EE, my reference is 30cm for 1ns ...

(08-01-2020 08:41 PM)johanw Wrote:  Are all these ancient units still used in papers? I still remember the scolding I got when I entered wavelengths in Ångström (1Å = \(10^{-10}\)m) in my masters thesis. I had to change it to nm before I could get a passsing grade, the faculty had a strict SI-only policy.

Non-SI units are very common in astronomy, think of the old parsec (distance where a length of 1AU is seen under an angle of 1 arc-second , with 1AU being the average Earth-Sun distance :-)
The parsec seems now less used and often replaced by the light-year (1 pc is about 3 ly), but is still used for instance for the Hubble constant (cosmological expansion) Ho ≈ 70 km/s/Mpc.

Also masses of stars are generally expressed not in kg but in solar mass, and so on.

A funny coincidence: there are (about) as many km in one light-year than Ångström in one km.

J-F
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Messages In This Thread
Estimation quiz! - EdS2 - 07-30-2020, 10:54 AM
RE: Estimation quiz! - Paul Dale - 07-30-2020, 11:27 AM
RE: Estimation quiz! - cruff - 07-30-2020, 01:00 PM
RE: Estimation quiz! - Paul Dale - 07-30-2020, 01:04 PM
RE: Estimation quiz! - cruff - 07-31-2020, 12:01 AM
RE: Estimation quiz! - KeithB - 07-30-2020, 01:56 PM
RE: Estimation quiz! - Paul Dale - 07-30-2020, 10:25 PM
RE: Estimation quiz! - Albert Chan - 07-30-2020, 02:13 PM
RE: Estimation quiz! - Werner - 07-30-2020, 02:24 PM
RE: Estimation quiz! - Massimo Gnerucci - 07-30-2020, 02:34 PM
RE: Estimation quiz! - Albert Chan - 07-30-2020, 03:10 PM
RE: Estimation quiz! - rprosperi - 07-30-2020, 04:20 PM
RE: Estimation quiz! - Werner - 07-30-2020, 05:37 PM
RE: Estimation quiz! - Albert Chan - 07-30-2020, 06:10 PM
RE: Estimation quiz! - rprosperi - 07-30-2020, 08:03 PM
RE: Estimation quiz! - EdS2 - 07-31-2020, 01:26 PM
RE: Estimation quiz! - Paul Dale - 07-31-2020, 01:40 PM
RE: Estimation quiz! - Valentin Albillo - 07-31-2020, 02:33 PM
RE: Estimation quiz! - Paul Dale - 08-01-2020, 01:09 AM
RE: Estimation quiz! - EdS2 - 08-01-2020, 06:48 AM
RE: Estimation quiz! - Thomas Okken - 08-01-2020, 07:30 AM
RE: Estimation quiz! - Massimo Gnerucci - 08-01-2020, 10:09 AM
RE: Estimation quiz! - Valentin Albillo - 08-01-2020, 11:16 PM
RE: Estimation quiz! - ijabbott - 08-01-2020, 05:24 PM
RE: Estimation quiz! - johanw - 08-01-2020, 08:41 PM
RE: Estimation quiz! - J-F Garnier - 08-02-2020 07:56 AM
RE: Estimation quiz! - SlideRule - 08-02-2020, 12:23 PM
RE: Estimation quiz! - Paul Dale - 08-02-2020, 01:10 PM
RE: Estimation quiz! - EdS2 - 08-02-2020, 03:13 PM
RE: Estimation quiz! - Valentin Albillo - 08-02-2020, 04:02 PM
RE: Estimation quiz! - Maximilian Hohmann - 08-02-2020, 05:04 PM
RE: Estimation quiz! - Valentin Albillo - 08-02-2020, 05:54 PM
RE: Estimation quiz! - Maximilian Hohmann - 08-02-2020, 09:01 PM
RE: Estimation quiz! - Albert Chan - 08-02-2020, 11:36 PM
RE: Estimation quiz! - SlideRule - 08-02-2020, 11:04 PM
RE: Estimation quiz! - Albert Chan - 08-02-2020, 05:41 PM
RE: Estimation quiz! - EdS2 - 08-03-2020, 07:56 AM
RE: Estimation quiz! - Albert Chan - 08-03-2020, 11:00 AM
RE: Estimation quiz! - pinkman - 08-03-2020, 03:08 PM
RE: Estimation quiz! - SlideRule - 08-03-2020, 11:57 AM
RE: Estimation quiz! - Valentin Albillo - 08-03-2020, 03:10 PM
RE: Estimation quiz! - KeithB - 08-03-2020, 01:54 PM
RE: Estimation quiz! - EdS2 - 08-03-2020, 03:22 PM
RE: Estimation quiz! - SlideRule - 08-03-2020, 03:49 PM
RE: Estimation quiz! - EdS2 - 08-04-2020, 10:17 AM
RE: Estimation quiz! - Thomas Okken - 08-04-2020, 12:33 PM
RE: Estimation quiz! - EdS2 - 08-07-2020, 06:57 AM
RE: Estimation quiz! - Thomas Okken - 08-07-2020, 09:03 AM
RE: Estimation quiz! - Albert Chan - 08-07-2020, 12:56 PM
RE: Estimation quiz! - EdS2 - 08-08-2020, 07:35 AM
RE: Estimation quiz! - Albert Chan - 08-08-2020, 05:01 PM
RE: Estimation quiz! - Csaba Tizedes - 08-04-2020, 11:25 AM
RE: Estimation quiz! - Csaba Tizedes - 08-07-2020, 02:06 PM
RE: Estimation quiz! - Albert Chan - 08-05-2020, 02:29 PM
RE: Estimation quiz! - KeithB - 08-05-2020, 03:38 PM
RE: Estimation quiz! - Albert Chan - 08-05-2020, 04:22 PM
RE: Estimation quiz! - StephenG1CMZ - 08-05-2020, 06:12 PM
RE: Estimation quiz! - EdS2 - 08-08-2020, 05:25 PM
RE: Estimation quiz! - KeithB - 08-13-2020, 01:41 PM
RE: Estimation quiz! - Albert Chan - 08-16-2020, 11:24 AM



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