Cheap but decent Mini Tape Measure

[Harry WilkesParticipant @harrywilkes58467]

Posted by Flying Fifer on 12/01/2017 18:56:21:

Or use a bit of string !!!

Yes but how long is a piece of string ?

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Neil Wyatt on 12/01/2017 21:15:13:

I'm just eyeing my tape measure suspiciously …

.

Wow … on the seventh page, he drags the thread back onto topic [ish]

MichaelG.

[Another JohnSParticipant @anotherjohns]

Posted by Harry Wilkes on 12/01/2017 21:20:17:

Posted by Flying Fifer on 12/01/2017 18:56:21:

Or use a bit of string !!!

Yes but how long is a piece of string ?

Nooo!!! No String Theory, please!

(for those who are not familiar with "String Theory", google it…)

JohnS.

[DodParticipant @dod]

All them protons flying around in a vacuum in Trafalgar Square with excited Caesium at the speed of light is a bit of overkill to measure how thick a short lump of wood is to see if it is actually a plank.

[John FlackParticipant @johnflack59079]

This may be a tad theoretical but what would the speed of light if you lived on the sun?????????????

[AjohnwParticipant @ajohnw51620]

I was idly wondering about something the other day – just in case. Say I have this motor with a certain power doing some rpm or the other fully loaded and I wanted to work out the torque in terms of force via it's feet on the plate it's mounted on.

Thanks to this thread I was wondering if I would do the sums in metric or imperial.

John

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Edited By Ajohnw on 13/01/2017 20:13:19

[Mike PooleParticipant @mikepoole82104]

I think the speed of light is a constant, sitting on the sun could be a bit on the warm side but my wife would probably be cold.

Mike

[JimmieSParticipant @jimmies]

Back to the mm v cm discussion. Called into a Polish dressmaker to get trouser's legs shortened by 5 and a half cm. "Sorry" she replied reaching for her tape. "could you show me?" I pointed at 5.5 CM and she replied " you mean 2 1/4 inches."

I think I will give up trying to make life easier for other folk!

[Allan BParticipant @allanb]

I was with a student the other day, and I asked him to set a vernier height gauge to 25mm, left him to it, and returned a few min later, and instantly I knew it was wrong, way too high, and it went as such….

Me "are you sure that is right?"

student "yes"

Me "can you explain how you came to set it to that height?"

student "well 25mm is 2.5cm so I set it to 2.5cm"

me "can you show me on the scale where 2.5cm is?"

student points to 2.5 inches

I will just leave that one there

[JimmieSParticipant @jimmies]

Allan, remember the old saying ' a teacher never retires early – it is always too late'. Wonder why?

[John FlackParticipant @johnflack59079]

Joking aside I am having sleepless nights regarding the speed of light . Is it a universal constant or would it be different on each planetary surface. My model is that the sun is like a cannon firing electro magnetic waves across the universe. My thoughts are that the initial burst of energy is at a higher speed than the trajectory which follows and the speed of the waves will slow over a distance as the energy dissipates to zero, this suggests that the speed of light is variable and that it will be no more than an average speed when calculated over a fixed distance. Is my thinking flawed???????

[Allan BParticipant @allanb]

Posted by John Flack on 14/01/2017 11:02:17:

Joking aside I am having sleepless nights regarding the speed of light . Is it a universal constant or would it be different on each planetary surface. My model is that the sun is like a cannon firing electro magnetic waves across the universe. My thoughts are that the initial burst of energy is at a higher speed than the trajectory which follows and the speed of the waves will slow over a distance as the energy dissipates to zero, this suggests that the speed of light is variable and that it will be no more than an average speed when calculated over a fixed distance. Is my thinking flawed???????

you are correct in your thinking from what I can remember as to how it is generated, and if it is generated in an atmosphere then your thinking on the slowing down would be correct as there is other apects to be taken into consideration, but as the sun and other sun's actually sit in a vacume then there is nothing else to act on the engery waveform on its travels so it stays at a constant velocity.

but I will stand corrected on this if someone has any other thoughts

Allan

[Allan BParticipant @allanb]

Posted by JimmieS on 13/01/2017 21:17:25:

Allan, remember the old saying ' a teacher never retires early – it is always too late'. Wonder why?

yes I know that saying, and it is never more in my thoughts than at the moment

[Tim StevensParticipant @timstevens64731]

John asks if his thinking is flawed.

Yes, John, I am afraid it is. At least, the science on which you rely is flawed, and so the thinking which follows cannot be correct. Light is not affected by air resistance or any similar effect, it does not use up its energy as it whizzes along. It is affected very slightly by gravity (which does seem to contradict the universality of its motion) but I think the speed remains the same. What alters with gravity is the velocity, which in science terms combines speed and direction.

And in a black hole there is so much gravity that the light cannot escape, but in such places the ideas of time, direction, etc go all peculiar, too.

I think.

Regards, Tim

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Tim Stevens on 14/01/2017 11:39:35:

John asks if his thinking is flawed.

Yes, John, I am afraid it is. At least, the science on which you rely is flawed, and so the thinking which follows cannot be correct. Light is not affected by air resistance or any similar effect

.

To develop that thought a little …

The speed of light in vacuo is [by mainstream dogma] asserted to be a fundamental constant.

… but that is the fastest that light can go; and it is demonstrably slowed-down by passing through various media [which is, of course, the foundation of refractive optics].

MichaelG.

.

http://www.physicsclassroom.com/class/refrn/Lesson-1/Optical-Density-and-Light-Speed

Edited By Michael Gilligan on 14/01/2017 12:51:59

[Keith Rogers 2Participant @keithrogers2]

Amazing how this thread has gone from the humble tape measure to the discussion of the speed of light.

That's forums for you

Keith.

[Geoff TheasbyParticipant @geofftheasby]

Check out Cerenkov Radiation.

Geoff

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Geoff Theasby on 14/01/2017 13:43:53:

Check out Cerenkov Radiation.

Geoff

.

… and my recent posting on the 'beauty of tools' thread

MichaelG.

[John FlackParticipant @johnflack59079]

Checked out Cherenkov radiation……. Gives you a headache. Simple question is the term 'space' the same as 'vacuum' I find the concept of a vacuum containing a universe contradictory!

[pgk pgkParticipant @pgkpgk17461]

Posted by John Flack on 14/01/2017 19:28:05:

Checked out Cherenkov radiation……. Gives you a headache. Simple question is the term 'space' the same as 'vacuum' I find the concept of a vacuum containing a universe contradictory!

'course not.. lots of stuff in space and doubtless someone will have average particles per metre^3 or Km^3.. why the lensman with his bergenholm (inertialess condition) could only travel at the speed in which the power of his propulsion equated to the density of matter which fortunately was a lot lower intergalactically than intragalactically

[Geoff TheasbyParticipant @geofftheasby]

John,

Not really headachey, Particles, which travel at the speed of light, emitted by radioactive materials underwater, are slowed by the Moderator (Water) The speed of light in water is lower, so according to Newtonian physics the absorbed energy is emitted as blue light.

Geoff

[AjohnwParticipant @ajohnw51620]

My truly small pocket tape arrived this morning.

**LINK**

It does seem to be well made so in my view worth the price. The spring return is so fast it could probably be used as a weapon. It might even cut a finger.

Weight 35g and none iso as it's marked in mm and cm as most do with the 10's in red. Nice clear scale as well.

Thanks to brexit the price has now gone up by 24p since I bought it on the 5th. Pity I didn't find them last time I looked, well over 12 months ago.

I asked at a shop why I couldn't buy a quality really small tape. Guess it's down to price but while it's rather steep providing it lasts I don't mind that.

John

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Edited By Ajohnw on 17/01/2017 11:30:44

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