# Singlespeed & Fixed Gear - Help me mathletes!

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View Full Version : Help me mathletes!

the pope
05-18-08, 07:32 PM
Question from the back of the class:

Word problem.

A flat bar, 46 centimeters long with a 5 degree sweep, will sweep back how many centimeters from the center to an end. I realize that the sweep in a flat bar does not start in the center but I've shortened the measuring distance to (hopefully reasonably accurately) compensate for this.

Thanks!

sp00ki
05-18-08, 07:36 PM
1) pencil
2) paper
3) ruler
4) protractor

surely you have these...

the pope
05-18-08, 07:38 PM
What's a protractor?

sp00ki
05-18-08, 07:44 PM
http://mathforum.org/dr.math/gifs/protractor.gif

it's a simple tool which allows you to draw angles.

if you have a printer:
1) type pdf protractor into google
2) print it out
3) make a dot where the anchor point is
4) make a dot where the 5 is and another where 0 is
5) draw a line from the anchor dot to the 5 dot; another from the anchor to 0

the line from anchor to the 5 dot is a 5 degree sweep. draw a 46mm (or whatever) line from the anchor through the 5 with a ruler. that's half the length of your bar. the rest should work itself out as you go.

the pope
05-18-08, 07:45 PM
Oh, sweet idea. Thanks.

Peedtm
05-18-08, 07:48 PM
Put the flat part against a wall and measure from the wall to whatever part you're curious about

Edit: Or solve tan(x/23)= pi/36 (5 degrees in radians)

the pope
05-18-08, 07:49 PM
I don't have the part yet. Wondering if I'll need a longer stem - and how much longer.

Measured. At 25 cm length I get a rise of 2 cm. That's a ballpark.

Peedtm
05-18-08, 08:02 PM
If you consider the slope (from math, 'member?) is pi/36, this is ~.087 cm of rise per cm of run. If you extend that for 25 cm (25 X .087), that equals 2.175cm. So I concur, sir. Go to it.

MIN
05-18-08, 08:34 PM
sin(5)*(46/2)=~2cm of backsweep

this translates to about 1.5cm in extra stem reach requirement because in reality hand placement is not at the end of the bar but about 5cm from the end.

the pope
05-18-08, 08:40 PM
Smarties.

dervish
05-18-08, 09:23 PM

vobopl
05-19-08, 12:49 AM
Question from the back of the class:

Word problem.

A flat bar, 46 centimeters long with a 5 degree sweep, will sweep back how many centimeters from the center to an end. I realize that the sweep in a flat bar does not start in the center but I've shortened the measuring distance to (hopefully reasonably accurately) compensate for this.

Thanks!

Type this: 23*sin(2*pi*5/360) to google search box and mouse over to get 2 cm and a change.

raster
05-19-08, 02:11 AM

vobopl
05-19-08, 02:41 AM

:love: someone got bored with 80% project

kemmer
05-19-08, 09:33 AM
Holy ****, that's amazing. Google is totally going to take over the universe. Maybe this is how the trade federation starts.

vobopl
05-19-08, 09:51 AM
How about unit conversions (inches to metric etc.) paste that: 20 inches in cm and mouse over :innocent:

Yoshi
05-19-08, 11:50 AM
But can google do Gauss-Jordan elimination?

MIN
05-19-08, 12:20 PM
But can google do Gauss-Jordan elimination?

No but it finds online calculators for linear algebra (http://http://www.google.com/search?hl=en&rls=SUNA%2CSUNA%3A2006-37%2CSUNA%3Aen&q=linear+algebra+calculator)!

tx_what_it_do
05-19-08, 02:23 PM
can google do statics? not statistics, statics