A Sky, cable and digital tv forum. Digital TV Banter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » Digital TV Banter forum » Digital TV Newsgroups » uk.tech.digital-tv (Digital TV - General)
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

uk.tech.digital-tv (Digital TV - General) (uk.tech.digital-tv) Discussion of all matters technical in origin related to the reception of digital television transmissions, be they via satellite, terrestrial or cable. Advertising is forbidden, with no exceptions.

Hopeless at maths



 
 
Thread Tools Display Modes
  #11  
Old March 30th 17, 10:54 PM posted to uk.tech.digital-tv
Norman Wells[_6_]
external usenet poster
 
Posts: 951
Default Hopeless at maths

On 30/03/2017 22:40, Tim+ wrote:
Bill Wright wrote:
I'm hopeless at maths, but I'm trying to get something across to an
intelligent child. So, if the distance from here to London (250km) is
represented by the thickness of a hair (0.2mm) how far is a light year?
It doesn't have to be a hair; it could be anything familiar and small.

It's 2.5 million light years to the Andromeda Galaxy; that's what we're
discussing.

Help!

Bill


Why use hair widths as an analogy? Most of us have no idea how thick a hair
is. Surely the standard unit of length/distance is the double decker bus?
;-)


I wouldn't argue with the British Standard Bus, but what you need for
comprehension of huge distances is something pretty big, and much bigger
than a bus, so the multiplication factor you need is lower. It's silly
to introduce something smaller like a hair.

  #12  
Old March 30th 17, 11:02 PM posted to uk.tech.digital-tv
Tim+[_4_]
external usenet poster
 
Posts: 191
Default Hopeless at maths

Norman Wells wrote:
On 30/03/2017 22:40, Tim+ wrote:
Bill Wright wrote:
I'm hopeless at maths, but I'm trying to get something across to an
intelligent child. So, if the distance from here to London (250km) is
represented by the thickness of a hair (0.2mm) how far is a light year?
It doesn't have to be a hair; it could be anything familiar and small.

It's 2.5 million light years to the Andromeda Galaxy; that's what we're
discussing.

Help!

Bill


Why use hair widths as an analogy? Most of us have no idea how thick a hair
is. Surely the standard unit of length/distance is the double decker bus?
;-)


I wouldn't argue with the British Standard Bus, but what you need for
comprehension of huge distances is something pretty big, and much bigger
than a bus, so the multiplication factor you need is lower. It's silly
to introduce something smaller like a hair.



Tankfuls of diesel (say 500 miles) would be more meaningful to adults,
maybe not a child though.

1 lightyear would require about 11,731,392,000 tankfuls. 2.5 million light
years rather more. ;-)

Tim

--
Please don't feed the trolls
  #13  
Old March 31st 17, 07:26 AM posted to uk.tech.digital-tv
Mark Carver[_2_]
external usenet poster
 
Posts: 353
Default Hopeless at maths

On 30/03/2017 20:53, Paul Ratcliffe wrote:
On Thu, 30 Mar 2017 20:00:32 +0100, Mark Carver
wrote:

So in 2.5 years

2.3635637 x 10^16 metres

2.3635637 x 10^13 km

So 2.3635637 x 10^13 km / 250 x 10^3 = 9.4542548 x 10^7


Yeah, but he said 2.5 million light years, so multiply that by 10^6.


Bugger. So he did. Anyway I thought the SI units for comparative scale
were football pitches, London buses, or Olympic sized swimming pools ?




--
Mark
Please replace invalid and invalid with gmx and net to reply.
  #14  
Old March 31st 17, 08:26 AM posted to uk.tech.digital-tv
Robin[_8_]
external usenet poster
 
Posts: 470
Default Hopeless at maths

On 30/03/2017 19:39, Bill Wright wrote:
I'm hopeless at maths, but I'm trying to get something across to an
intelligent child. So, if the distance from here to London (250km) is
represented by the thickness of a hair (0.2mm) how far is a light year?
It doesn't have to be a hair; it could be anything familiar and small.

It's 2.5 million light years to the Andromeda Galaxy; that's what we're
discussing.

Help!

I think that's too big a step. You need one or more intermediate senses
of scale - eg our nearest neighbour star. My favourite for that with
groups was to give one a dry pea to represent the Earth; a second a
beach ball to represent the sun - and send them to stand about 60m away
(back of the hall will do if it's raining!); and then ask for a
volunteer to take a second beach ball to represent Alpha Centauri. And
then ask the volunteer to send us a postcard from New Zealand.

And you've probably seen that it's more common to try to get across such
issues of scale in terms of time to travel rather than scale. Eg if
there were a motorway to Andromeda it would take 10 million years - to
go *1* light year.



--
Robin
reply-to address is (intended to be) valid
  #15  
Old March 31st 17, 09:21 AM posted to uk.tech.digital-tv
Chris Green
external usenet poster
 
Posts: 148
Default Hopeless at maths

Mark Carver wrote:

Bugger. So he did. Anyway I thought the SI units for comparative scale
were football pitches, London buses, or Olympic sized swimming pools ?

Exactly! :-)

..... silly analogies 'r us.

--
Chris Green
·
  #16  
Old March 31st 17, 09:25 AM posted to uk.tech.digital-tv
Brian Gaff
external usenet poster
 
Posts: 6,958
Default Hopeless at maths

The crux of the problem is buried in this calculation in fact, but I think
the scaling is the wrong way around. What he wants is actual distance in the
same measurement units as used by the metric system used to measure the
hair. So the equation needs to work the other way around, and its far too
early for my remaining cells to do that, so I'll leave it to others!

Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"Mark Carver" wrote in message
...
On 30/03/2017 19:39, Bill Wright wrote:
I'm hopeless at maths, but I'm trying to get something across to an
intelligent child. So, if the distance from here to London (250km) is
represented by the thickness of a hair (0.2mm) how far is a light year?
It doesn't have to be a hair; it could be anything familiar and small.

It's 2.5 million light years to the Andromeda Galaxy; that's what we're
discussing.


Speed of light, 299,792,458 m/s

Number of seconds in a year

60 x 60 x 24 x 365 = 31,536,000 seconds

Therefore in one year light travels 31.536 x 10^6 x 299.792458 x 10^6

= 9.4542547 x 10^15 metres

So in 2.5 years

2.3635637 x 10^16 metres

2.3635637 x 10^13 km

So 2.3635637 x 10^13 km / 250 x 10^3 = 9.4542548 x 10^7

Therefore if a human hair represents 250km, it's 94.5 million hairs to
Andromedia



--
Mark
Please replace invalid and invalid with gmx and net to reply.



  #17  
Old March 31st 17, 10:49 AM posted to uk.tech.digital-tv
David[_14_]
external usenet poster
 
Posts: 54
Default Hopeless at maths

On Fri, 31 Mar 2017 07:26:05 +0100, Mark Carver wrote:

On 30/03/2017 20:53, Paul Ratcliffe wrote:
On Thu, 30 Mar 2017 20:00:32 +0100, Mark Carver

wrote:

So in 2.5 years

2.3635637 x 10^16 metres

2.3635637 x 10^13 km

So 2.3635637 x 10^13 km / 250 x 10^3 = 9.4542548 x 10^7


Yeah, but he said 2.5 million light years, so multiply that by 10^6.


Bugger. So he did. Anyway I thought the SI units for comparative scale
were football pitches, London buses, or Olympic sized swimming pools ?


Perhaps this can help?

https://www.theregister.co.uk/Design/page/reg-standards-converter.html

Cheers

Dave R

--
AMD FX-6300 in GA-990X-Gaming SLI-CF running Windows 7 Pro x64

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT. The time now is 01:17 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.SEO by vBSEO 2.4.0
Copyright 2004-2017 Digital TV Banter.
The comments are property of their posters.