Metric/Imperial Rulers

[ian16th]

Has anyone measured the speed of light? - or is it just assumed from calculations?

According to Max Boyce, Gerald Davies could switch off his bedroom light, and get across the room and into bed before the room went dark.

[Pontius Navigator]

When I needed to check how many zero's, I used the Light Program's 1500 metres and 200 Kc/s.

Therefore 1 Hz=1.0101010101 c/s

Yes?

[Fox3WheresMyBanana]

The speed of light can be measured by second formers these days; it is an experiment I used to do with them. One needs a laser which can be pulsed, a light dependent resistor, a storage oscilloscope in the MHz range, and a long corridor (about 50 foot will do). Send pulse down corridor, reflect it off a mirror, receive it back on the LDR. Measure the time difference between the trigger pulse and the received reflected pulse, and Robert's your father's brother. Second formers love this kind of thing - they get to use spray guns in the dark for beam detection, make 'Danger- laser!' signs, and guard corridor doors from intruders - "Back off man, I'm a scientist!", etc. I used to get the Sixth form to set up and test the experiment, the second formers to do it, and the fourth formers to do it properly by varying the distance travelled and doing repeats.

[Pontius Navigator]

See in the paper today a snowflake, must be 55-60, complaining he was taught metric and doesn't know imperial.

Would his 1.95m car pass under a height limit of 6 ft 4 in?

It really is a shame that some people only know half the weights and measures. How would he manage in the USA? How would he manage in the real world with fuels in lb, kg, l, imp gal, us gal etc?

How did British housewives manage in Cyprus with Okes?

https://en.m.wikipedia.org/wiki/Cypriot ... easurement

[Undried Plum]

It really is a shame that some people only know half the weights and measures. How would he manage in the USA?

He'd get a job on a NASA Mars project.

They tried using both metric and Imperial on the same project. The navigators used metric and the propulsion guys used Imperial. They didn't bother with conversion factors. Result: crash.

[ian16th]

How did British housewives manage in Cyprus with Okes?

https://en.m.wikipedia.org/wiki/Cypriot ... easurement

SM got on fine with it, and the Pic (sp)
Dunno how to spell it but it was a unit of linear measure, about 2 foot.
It was used in haberdashers, for buying material for dresses.
Greek Cypriot dressmakers were amazing. Just show them a picture in a women's magazine, an estimate/thumb suck of material quantity was made, then the made to measure dress appeared a couple of days later.

[Pontius Navigator]

When we metricated I measured up for some curtains. Each 1.2 metres (for instance) much easier than 3 feet 10 inches each so 15 ft 4 in material needed etc.

"Did we want it cutting" Yes please.

When we got it it was in 4 different lengths from 3 feet to 5. The ship owner said we had confused his cutter as she didn't understand metric.

Would you believe, 40 years later, different store and they still got it wrong.

[G-CPTN]

When we metricated I measured up for some curtains. Each 1.2 metres (for instance) much easier than 3 feet 10 inches each so 15 ft 4 in material needed etc.

"Did we want it cutting" Yes please.

When we got it it was in 4 different lengths from 3 feet to 5. The shop owner said we had confused his cutter as she didn't understand metric.

Would you believe, 40 years later, different store and they still got it wrong.

Why not fold the material in half (and cut) then fold each piece in half (and cut) - no measurements needed . . .

[Fox3WheresMyBanana]

You're thinking again - Stop It!

[Slasher]

It's 299 792 458 m/s

Um....yep. I booboo'd the 792 bit. Thanks Fox.

I think it was sometime in the early '80s that the 300 mill/sec affair occurred when the metre was being redefined.

[Sisemen]

Having spent the last almost 30 years in Oz I now think in kilometres, litres and degrees C, but flying is still feet and knots!

[Fox3WheresMyBanana]

The speed of light is now defined from the definition of the second, and the metre similarly derives from the other two. The constant from theory is of course the speed of light, the other two are dependent on the relative velocity of the observer.
As for what time actually is, one can do no better than quote Einstein:

“When you sit with a nice girl for two hours you think it's only a minute, but when you sit on a hot stove for a minute you think it's two hours. That's relativity.”

[Slasher]

Question re Relativity (Fox don't answer! )

I'm going to Proxima Centauri which is 4.25 light years distant, and I'm gonna travel at 99.9999999999999999999999999999999999999% of the speed of light.

I'm going to sit my bare bum on a hot stove for the duration of my trip. It's an electric stove with an unlimited AC source.

The flight by my onboard clock took 10 secs, but you blokes back on Earth measured it taking 4.26 years.

By the time I arrive at Proxima Is my butt only badly singed or burnt to a total crisp after a four and a quarter year grilling?

[Fox3WheresMyBanana]

[llondel]

The speed of light in free space is a foot per nanosecond for a lot of engineering purposes.

[ricardian]

When I needed to check how many zero's, I used the Light Program's 1500 metres and 200 Kc/s.

Therefore 1 Hz=1.0101010101 c/s

Yes?

Light Programme (now Radio 4) changed to 198 kHz in February 1988. Power output of Droitwich is about 500 megawatts.

[Pontius Navigator]

Just watching the London marathon and the metric Horlicks.

BBC check point. - 35 km. Down the Mall, 200 metres to go. And distance caption with time in miles.

Latest caption 40 km point. Had to get the whiz wheel out to find how much further to go - about 2km or just over the mile.

Surprised they haven't metricated the whole nine yards.

[Fox3WheresMyBanana]

"The whole 8.22 metres" doesn't have the same ring to it

[Slasher]

Neither does "Walk a 1.6km in my shoes" doesn't either.

[barkingmad]

Some time ago I watched an archaeological prog on the box about a recently discovered shipwreck which had been identified as one of Napoleon's warships.
I got a strange sense of satisfaction when the French archivist dragged out the original plans & drawings for the ship and read off the dimensions in Imperial feet & inches as originally written on said blueprints.
When & why did was SI introduced? Was it the same pique at English colonialism which provoked the French (and the Yanks) to decide to drive on the "wrong side" of the road? Although our tea-dumping friends on far side of the Atlantic stayed with Imperial units they did muck about with the gallon with some strange conversion factor.