Did I miss something?

Submitted: Saturday, Nov 06, 2004 at 13:18
ThreadID: 17582 Views:2768 Replies:8 FollowUps:23
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Was I asleep? Is it just me?

If you build a house, you will be asked what roof pitch you want........... in degrees.

If you buy a 4 x 4, you will be told approach, departure, & ramp-over........... in degrees.

Why then, when you drive down roads here in South Australia, are we being told the severity of the fall in percent? Percent of what? If 90 degrees is straight down, is that 100 %?
Why cant it just be in degrees? Or better still.........radians......... what gives?

Cheers

I'm running at 100% ( 90 degrees)! Wolfie
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Reply By: toymn8r - Saturday, Nov 06, 2004 at 13:29

Saturday, Nov 06, 2004 at 13:29
Apparently the sudden stop at the bottom hurts less in percentages than in degrees.
So its obviously a safety type thing.
Makes sense to me I think
AnswerID: 83231

Follow Up By: Lone Wolf - Saturday, Nov 06, 2004 at 13:30

Saturday, Nov 06, 2004 at 13:30
No, no,no........... wrong!!!!!

You see, if a road is say 45 degrees, that is what 50 %?

50 % has gotta hurt waaaaaay more than 45..........

Cheers

Wolfie
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Reply By: toymn8r - Saturday, Nov 06, 2004 at 13:36

Saturday, Nov 06, 2004 at 13:36
I see what you mean. So if you are travelling horizontally straight ahead you would be doing 180 degrees or zero%, but if you hit a stationary object it would depend on the degree of difficulty as to the percent of damage.
Yeah I got it good now.

Thanks for the clarification
AnswerID: 83232

Reply By: Member - Peter Z (VIC) - Saturday, Nov 06, 2004 at 14:04

Saturday, Nov 06, 2004 at 14:04
A road gradient is usually expressed in percentage terms from the engineering viewpoint. It is the rate of climb or fall in relation to the horizontal distance .

For instance, if an advisory road sign states that the particular gradient is 50% , then you will rise or descend half the horizontal distance within that distance, so a 50% gradient is equal to 45 degrees. Gawd I've made this seem complicated !

Likewise a 10% grade rises or falls one tenth of the distance.
Hell I bet yer glad I'm finished !
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Follow Up By: Lone Wolf - Saturday, Nov 06, 2004 at 14:33

Saturday, Nov 06, 2004 at 14:33
... so.... is that like there is always 180 degrees in a triangle.......... or ............. 200%?

Just imagine........... poor bloody Pythagorus would be turning in his grave.......... in 2 degree increments!!

Cheers

Just bloody steep, okay? Wolf
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Follow Up By: Member - Roachie (SA) - Saturday, Nov 06, 2004 at 15:08

Saturday, Nov 06, 2004 at 15:08
Wolfie......

Quote..."Just imagine........... poor bloody Pythagorus would be turning in his grave.......... in 2 degree increments!! "......

Sorry mate.....wrong, wrong, wrong....... He would actually be turning in his grave in 1% increments......Please, get this right will ya......it's a matter of life and death of course.

Now back to percentages when measuring gradients..........

One of my other interests/hobbies is trains, both model and full size. Now our railway mates here in Oz refer to line gradients as "one in XXX". EG: a hill which ascends @ 1 foot every 66 feet is known as a "1 in 66". This was very common (and probably still is) and gave the train crew a really good idea of what sort of fire they had to put on the ol' girl to get over that sucker.
Meanwhile, our gawd-damn Yanky mates, have always referred to their gradients (of course the yanks have a better class of gradient than ours here "down-under"...haha) as percentages. Hence for a 1 in 66 gradient as we know it, the yanks would sign-post that for the train crew as 1.3% (I think...LOLOL). I reckon it would have been a pre-requisite for a yank to have a degree in mathematics (or "math" as they call it!!!.....note no "s") to get a job as a train driver.
If the signage was up to me, I would simply put a sign at the top of a steep hill saying things like:
"Slow Down Dopey, there's a bit a downward hill in front of ya". (for a moderate hill).
"You might wanna hit 2nd gear bloke" (for a slighty steeper decline)
"Both feet on the middle pedal fella.....right NOW" for a pretty bad hill
and finally.....
"If you're doing more than 25kph at this stage, take your hands off the wheel, bend over and kiss yer arze goodbye" for the mother of all drop offs....

Works for me....
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Follow Up By: Lone Wolf - Saturday, Nov 06, 2004 at 15:18

Saturday, Nov 06, 2004 at 15:18
Bill, when I lived at Gladstone, I did Guard duty on the Narrow Gauge from Gladstone to Wilmington every week. The ruling grade was 1 - 60. That was just out of Stone Hut if my memory serves me right. Was a funny sort of clause as well, because we would all get paid an allowance if the ruling grade was higher than 1 - 61!!

Money for Jam, those were the days!!

Anyway......... I'm just waiting for some smart prick to walk into my Sheet Metal Shop, and say........" Hey Mister, can you bend this piece of metal to 32%?" Aggghhhhhhhhh!!!

Cheers

Wolfie

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Follow Up By: Rosco - Bris. - Saturday, Nov 06, 2004 at 15:49

Saturday, Nov 06, 2004 at 15:49
45 degrees = 1 in 1
(1/1)*100 = 100%

1 in 6
(1/6)*100 = 16.6667%

1 in 2
(1/2)*100 = 50%

Get the picture??

Cheers
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Follow Up By: Lone Wolf - Saturday, Nov 06, 2004 at 17:03

Saturday, Nov 06, 2004 at 17:03
So, what your saying is.......... if you got a hill, and it's 46 degrees.......... it's actually MORE than 100%?

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Follow Up By: Rosco - Bris. - Saturday, Nov 06, 2004 at 17:38

Saturday, Nov 06, 2004 at 17:38
Yup

103.5530314%

90 deg = infinity% ..... (any value/0 = infinity) (infinity*100 = infinity)

89.9999 deg = 57295779.51%

Tricky huh??

See why ya need a Landie ... ;-))))))
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Follow Up By: Lone Wolf - Saturday, Nov 06, 2004 at 17:45

Saturday, Nov 06, 2004 at 17:45
.... whoa!!!!!!!

Well, I take my hat ( bandana ) off to you Rosco. I would have always thought that 45 degrees was 50 %.

I had a look on Google, and the dudes that ride bikes & run up hills ( wankers , that's why we have 4 wheel drives.........), say exactly the same thing.

Thankyou, and I'll bet there are quite a few lurkers THAT DID NOT KNOW!!!

All together now..."Thank You Mr. Wolfie for asking a question we were too afraid to ask!!"

"That's okay boys & girls, but remember one thing.... once your over the age of 45, you are 100% fu.......ed!!!"

Cheers

Wolfie
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Follow Up By: fisho64 - Sunday, Nov 07, 2004 at 03:28

Sunday, Nov 07, 2004 at 03:28
then you will rise or descend half the horizontal distance within that distance, so a 50% gradient is equal to 45 degrees. Gawd I've made this seem complicated !

to decend or rise half the horizontal distance, is actually 30 degrees?
a triangle with a 45 deg side will have the other 2 sides equal, in other words travel the same distance up or down as the horizontal distance
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Follow Up By: Rob! - Monday, Nov 08, 2004 at 11:46

Monday, Nov 08, 2004 at 11:46
Yep rosco's right.

It is a measure of how high you travel versus how far you travel.
So going...
1m up and 1m forward = 1/1 = 100% = 45 deg
1m up and 2m forward = 1/2 = 50% = 26.57 deg
1m up and 5m forward = 1/5 = 20% = 11.31 deg

or in other words, for every 5 metres you travel forward you go up 20%, or 1 metre.

So for angles greater then 45 degrees, you actually travel up more then you travel forward,

so 200% (2/1) would be to travel up 2 metres but go forwrd only 1 metre (63.42 deg)

My head hurts..

R.
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Follow Up By: Member - Rohan K - Tuesday, Nov 09, 2004 at 15:40

Tuesday, Nov 09, 2004 at 15:40
And 66% = 1/3 = 1m up for 1.5 m forward = 33 degrees, which is about the maximum for most "normal" 4WDs

[ View Image]
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Follow Up By: Member - Rohan K - Tuesday, Nov 09, 2004 at 15:41

Tuesday, Nov 09, 2004 at 15:41
No! Argghhh! That's 1/1.5
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Reply By: Baz (NSW) - Saturday, Nov 06, 2004 at 16:18

Saturday, Nov 06, 2004 at 16:18
See Wolfie Landrover drivers are smart buy a Landie and you'll be smarter than the average Wolf, eh !!!
AnswerID: 83247

Follow Up By: Member - JohnR (Vic) - Saturday, Nov 06, 2004 at 18:00

Saturday, Nov 06, 2004 at 18:00
Baz,

it actually looks enough huff-an-puff to blow out the walls on Wolfies house of straw. Glad mine wasn't designed by him and I didn't have to follow the percentages when building a 28 degree pitch in the roof........
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Reply By: Bob of KAOS - Saturday, Nov 06, 2004 at 19:01

Saturday, Nov 06, 2004 at 19:01
While the poor bloody Beaumonts (one of my favourite names for South Australians) describe a gradient in terms of percentage, feel sorry for the 'septics' who still talk about pounds of thrust, foot pounds, feet per second, horsepower, 32nds of an inch and such like. I think one of the space shuttles was brought down over confusion regarding units. It just goes to show we should be using standardised units, and until something better comes along, SI units.
AnswerID: 83268

Follow Up By: navaraman - Saturday, Nov 06, 2004 at 19:35

Saturday, Nov 06, 2004 at 19:35
Why "Beaumonts" for S Aussies.

Metric is OK but give me feet and inches, stones and pounds, mpg anyday.

Anyway I'm off out for a couple of pints now, hic.
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Follow Up By: Member - Bradley- Saturday, Nov 06, 2004 at 20:29

Saturday, Nov 06, 2004 at 20:29
Geez Bob you had better feel sorry for me too !! , did all my engineering studies in Metric, became an Aircraft maint. engineer and have to do everything in imperial, ansett went bust , i worked mining for a while - metric again, now back on jets - imperial again ARhhhhhhh i dont know what is what anymore !!!! Cheers buddy
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Follow Up By: fisho64 - Sunday, Nov 07, 2004 at 03:31

Sunday, Nov 07, 2004 at 03:31
wasnt the shuttle it was one of the mars probes
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Reply By: peter in sa - Saturday, Nov 06, 2004 at 19:35

Saturday, Nov 06, 2004 at 19:35
LONE WOLFi now this has nothin to do with 4wding but you meantioned same thing about living in Gladstone i get a sniff that you were in the railways there if so did you now a Trevor Freer or Gordon Green cheer,s GREENDOG
AnswerID: 83273

Follow Up By: Lone Wolf - Saturday, Nov 06, 2004 at 23:49

Saturday, Nov 06, 2004 at 23:49
Trevor was the District Foreman.

Don't remember Gordon, I don't think..........

Cheers

Wolfie
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Reply By: peter in sa - Sunday, Nov 07, 2004 at 15:19

Sunday, Nov 07, 2004 at 15:19
Wolfie Gordon green is me old man he used to work long side of trevor as the costing assistant from 86 till 89 i reckon ,dad ended up retiring out of the railways there after 30 yrs of service cheer,s GREENDOG
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Reply By: Nudenut - Monday, Nov 08, 2004 at 09:28

Monday, Nov 08, 2004 at 09:28
? i'm more confused than ever!
what is the % if your going vertically up ie 90 degreeees to the earths surface?
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Follow Up By: Rosco - Bris. - Monday, Nov 08, 2004 at 09:34

Monday, Nov 08, 2004 at 09:34
Infinity %.

See above for explanation.

Cheers
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Follow Up By: Nudenut - Monday, Nov 08, 2004 at 09:41

Monday, Nov 08, 2004 at 09:41
thats a bloody big number!
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Follow Up By: Rosco - Bris. - Monday, Nov 08, 2004 at 09:55

Monday, Nov 08, 2004 at 09:55
Sure is.

If you've got a scientific calculator try Tan 90 degrees. You'll get "Error"
or something similar. 'Cause the answer is infinity.
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Follow Up By: Nudenut - Monday, Nov 08, 2004 at 10:28

Monday, Nov 08, 2004 at 10:28
ah ah so straight up is 90 degreeeeeees
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Follow Up By: Nudenut - Monday, Nov 08, 2004 at 10:35

Monday, Nov 08, 2004 at 10:35
tan(90) = -1.99520041 so says google
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Follow Up By: Rosco - Bris. - Monday, Nov 08, 2004 at 10:43

Monday, Nov 08, 2004 at 10:43
Try http://mathforum.org/library/drmath/view/54086.html
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