(Please visit one of our advertisers)

No donations or subscriptions are required

   OR   
   
Subscription choices:
Board Karma = 40  (3456 positive of 3838 votes is 40 %pts higher than a neutral 50%)
All Things (Safety Oriented) Motorcycle   
Username:
Password:
Save Password
Forgot your Password?

You can the entire collection of Safety Tip articles in a 33 Megabyte PDF Portfolio

 All Forums
 Off Theme
 Puzzles and Games
 New Watch
Member Previous Topic Discussion Topic Next Topic  

James R. Davis
Male Administrator
17375 Posts
[Mentor]


Houston, TX
USA

Honda

GoldWing 1500

Posted - 07/16/2008 :  9:40 AM Follow poster on Twitter  Join poster on Facebook as Friend    DetailDetail                        Like
Poll Question:
I recently bought a new watch. Unlike my older watch, a dead-on accurate digital, this one is analog. I wanted to test it to see how accurate it was.

Starting when the big hand and the little hand are both pointing to the '12', I used my digital watch to let exactly one hour and five minutes elapse and found that the big hand and the little hand of the analog watch were then both pointing to the '1' on the dial of my analog watch.

From that information I was able to determine the accuracy of my analog watch.

What did I discover about the new analog watch?

It was


Results:
Accurate   [62%] 52 votes 
Fast   [5%] 4 votes 
Slow   [5%] 4 votes 
Broken   [29%] 24 votes 
= Guests (22 votes)


Poll Status: Closed  »»   Total Votes: 84 counted  »»   Last Vote: 01/06/2009 9:53 AM 
rioguy
Ex-Member

Posted - 07/16/2008 :  10:46 AM
James,

It was broken

Because when the minute hand is at the 1, the hour hand should be 1/12th of the way from the 1 to the two.

You would have to make up a couple of simultaneous equations to see where they pass.

The test back at you is what are these equations?
Go to Top of Page

scottrnelson
Advanced Member
6943 Posts
[Mentor]


Meridian, ID
USA

Honda

XR650L, 790 Adv R

Posted - 07/16/2008 :  12:23 PM
quote:
Originally posted by rioguy

The test back at you is what are these equations?

If F is the fraction of distance around the face (0.0 and 1.0 are both at 12 exactly, 0.5 is at 6, 0.25 is at 3, and so on), and H is the current hour that we're in, wouldn't the equation be F = H / 11.0 ?

At least that's what I come up with after spending about ten seconds thinking about it.
Go to Top of Page
rioguy
Ex-Member

Posted - 07/16/2008 :  2:00 PM
The hour hand moves 1/12th of the distance the minute hand moves.

At 5 minutes after, the hour hand should have been 5/12ths of a minute past the 1.

That's my answer afer hours of thinking.

Go to Top of Page

crisis
Male Starting Member
5 Posts


Bothell, WA
USA

Kawasaki

Vulcan

Posted - 07/17/2008 :  12:48 PM
quote:
Originally posted by rioguy
The test back at you is what are these equations?



Solve x-i == x/12 for i=0,1,2,...,11
This gives 11 unique solutions (0 is duplicated). Modulo 1, these solutions are:
0, 1/11, 2/11, 3/11, 4/11, 5/11, 6/11, 7/11, 8/11, 9/11, 10/11

For example, the two hands coincide at 12 o'clock (0/11 of the way around the face), approximately 5.45 minutes after 1 (1/11 of the way around), 10.91 after 2, and so on.
Go to Top of Page

scottrnelson
Advanced Member
6943 Posts
[Mentor]


Meridian, ID
USA

Honda

XR650L, 790 Adv R

Posted - 07/17/2008 :  3:18 PM
quote:
Originally posted by crisis

This gives 11 unique solutions (0 is duplicated).

I'm curious if this is somehow different from my answer.
Go to Top of Page

bobby0824
Male Junior Member
45 Posts


Nokomis, FL
USA

Harley-Davidson

FXDCI

Posted - 08/06/2008 :  2:42 PM   Join poster on Facebook as Friend  
both hands on 12 = twelve o'clock
both hands on 1 = five minutes after one o'clock
therefore, accurate

Geez, you guys are way too technical.

Edited by - bobby0824 on 08/06/2008 3:49 PM
Go to Top of Page

sporty
Senior Member
338 Posts


north liberty, ia
USA

Harley-Davidson

Dyna & Sportster

Posted - 08/06/2008 :  10:10 PM
quote:
Originally posted by James R. Davis

I recently bought a new watch. Unlike my older watch, a dead-on accurate digital, this one is analog. I wanted to test it to see how accurate it was.

Starting when the big hand and the little hand are both pointing to the '12', I used my digital watch to let exactly one hour and five minutes elapse and found that the big hand and the little hand of the analog watch were then both pointing to the '1' on the dial of my analog watch.

From that information I was able to determine the accuracy of my analog watch.

What did I discover about the new analog watch?

It was




What happened to checkbox 5:
"Whats an analog watch?"
Go to Top of Page

James R. Davis
Male Administrator
17375 Posts
[Mentor]


Houston, TX
USA

Honda

GoldWing 1500

Posted - 08/07/2008 :  2:41 AM Follow poster on Twitter  Join poster on Facebook as Friend  
quote:
both hands on 12 = twelve o'clock
both hands on 1 = five minutes after one o'clock
therefore, accurate

Just so that you know ... Both hands on an analog watch are NEVER pointing to the 1 at the same time (or any hour other than 12). The small hand points to the 1 on that hour, but five minutes later it has moved beyond it when the large hand gets there.
Go to Top of Page

Daddio
Male Advanced Member
775 Posts
[Mentor]


Calera, AL
USA

Suzuki

Bandit 1250

Posted - 08/07/2008 :  7:51 AM
I realize that the hour hand would be ever so slightly past the one mark. If you want digital precision - you should stay with a digital watch. Really, your watch is "close enough" for 99.9 % of the folks that even know how to read an analog clock, thus, not broken. We really should be able to tell time to a reasonable degree even if there are no markings. A judgement of how two hands are pointed in relation to each other should be enough to let us know what time it is. If it is a very expensive watch, I say take it to a watchmaker that could realign the hands or test the movement. Of course, the hands probably did not exactly align at noon. If they did - the longer the watch ran - the larger the error should be at longer periods of time. If it is a cheap watch - you get what you pay for.
Go to Top of Page
Niebor
Ex-Member

Posted - 08/07/2008 :  8:29 AM
My grandson is six. When asked the time, he sneaks away and looks at one of the digital clocks. At our house digital clocks outnumber analog on the order of six to one, so he sees no reason to be concerned with being able to read an analog clock. We set him up by setting the analog clock 15 minutes fast. It was interesting to see him work through that inaccuracy. Ultimately, he decided the analog clock was broken.
Go to Top of Page

D R
Advanced Member
1053 Posts
[Mentor]


Northern, Virginia
USA

BMW

R1200RT

Posted - 08/07/2008 :  9:51 AM
quote:
Originally posted by Niebor

My grandson is six. When asked the time, he sneaks away and looks at one of the digital clocks. At our house digital clocks outnumber analog on the order of six to one, so he sees no reason to be concerned with being able to read an analog clock. We set him up by setting the analog clock 15 minutes fast. It was interesting to see him work through that inaccuracy. Ultimately, he decided the analog clock was broken.



Many years ago (when I was still on Active Duty with the Military), I was surprised to learn that Basic Training had added two remedial courses for the select few who might need them.

One was how to tell time with an analog clock (vs. digital).

The second one, believe or not, was how to tie a shoe/boot lace (for those raised with nothing but velcro).

With all the reliance on electronic technology today, I wonder if sometime in the future they might have to teach how to actually write with a pen/pencil.

Go figure.
Go to Top of Page

dfpd273
Male Senior Member
303 Posts


Princeville, IL
USA

Yamaha

warrior

Posted - 08/07/2008 :  9:56 AM
quote:
Originally posted by D R

With all the reliance on electronic technology today, I wonder if sometime in the future they might have to teach how to actually write with a pen/pencil.

Go figure.



Sorry off topic, but my step-son asked me which address went where while addressing an envelope the other day. He said he hadn't had to actually write on an envelope since he was in grade school. All his bills are paid online and he never pays attention when receiving mail.


Go to Top of Page

dmauray
Male Standard Member
100 Posts


Rockledge, Fl
USA

Harley-Davidson

FLHTK, FLSTFI

Posted - 08/07/2008 :  10:55 AM
I don't have an analog watch but my digital gains about 10 seconds a month. I set mine by the clock at Cape Canaveral (321-853-3333). That way you can check it over a longer period of time.
Go to Top of Page

scottrnelson
Advanced Member
6943 Posts
[Mentor]


Meridian, ID
USA

Honda

XR650L, 790 Adv R

Posted - 08/07/2008 :  11:34 AM
quote:
Originally posted by dmauray

I don't have an analog watch but my digital gains about 10 seconds a month. I set mine by the clock at Cape Canaveral (321-853-3333). That way you can check it over a longer period of time.

Just go to http://time.gov/ and you can have time accurate to the second right on your computer.

I have a clock at home that tunes in to WWV to get the exact time, and what I get from time.gov matches exactly.
Go to Top of Page
Niebor
Ex-Member

Posted - 08/07/2008 :  1:34 PM
quote:
Originally posted by rioguy

The hour hand moves 1/12th of the distance the minute hand moves.

At 5 minutes after, the hour hand should have been 5/12ths of a minute past the 1.

That's my answer afer hours of thinking.


I believe that would be 1/12, not 5/12.

I'm amazed at the sheer volume of math that can be thrown at this!

Since I concluded the slight difference in the hour hand would be difficult to even distinguish, I called it accurate.
Go to Top of Page

scottrnelson
Advanced Member
6943 Posts
[Mentor]


Meridian, ID
USA

Honda

XR650L, 790 Adv R

Posted - 08/07/2008 :  3:02 PM
quote:
Originally posted by Niebor

Since I concluded the slight difference in the hour hand would be difficult to even distinguish, I called it accurate.

So the word exactly in the original problem doesn't mean anything to you?

I hope you aren't designing airplanes or computer chips or anything else requiring exactness.
Go to Top of Page

sporty
Senior Member
338 Posts


north liberty, ia
USA

Harley-Davidson

Dyna & Sportster

Posted - 08/07/2008 :  10:48 PM
quote:
Originally posted by scottrnelson

quote:
Originally posted by Niebor

Since I concluded the slight difference in the hour hand would be difficult to even distinguish, I called it accurate.

So the word exactly in the original problem doesn't mean anything to you?

I hope you aren't designing airplanes or computer chips or anything else requiring exactness.



Like one of the Intel processors from many moons ago...???

:-O
-Willy
Go to Top of Page

scottrnelson
Advanced Member
6943 Posts
[Mentor]


Meridian, ID
USA

Honda

XR650L, 790 Adv R

Posted - 08/08/2008 :  7:55 AM
quote:
Originally posted by sporty

Like one of the Intel processors from many moons ago...???

Looks like we're going off topic again.

However, since I worked for Intel for a few years, I know a little bit about the FDIV bug in the Pentium processor. I worked with the guy who was involved in that part of the testing. For divide operations it used an iterative approach starting with a seed value that was looked up in a table. Starting with an initial seed saved two or three iterations for getting an accurate result, so it was faster that way. For some unknown reason, the first eight locations of the ROM with these initial values didn't get programmed properly and had zeroes in them. Divide operations using one of those values were less accurate.

The verification engineers should have checked the ROM values as well as just doing divide operations, but they didn't. If I were in charge of testing I would do that, and I make sure that chips I design are fully tested that way.

Some people are of the opinion that it is better to have people test to the specifications without knowing anything about the internal architecture of a chip, but I've never agreed with that. It's good to have people test chips when they don't know what's inside, but you also need people to test specific parts of the chip based on the design. There should have been test access to all ROMs to verify correct contents - I don't know if such a data path was present in that chip or not.

What this has to do with watches, I don't know, but it has a lot to do with being exact. In a chip design, all you need is one wrong bit out of 20,000,000 and it won't work right. Everything has to be exact.

And now, back to our regularly scheduled program on analog watch accuracy...
Go to Top of Page

Mrjava
Male Starting Member
1 Posts


Northridge, Ca
USA

Yamaha

VStar 1300

Posted - 08/22/2008 :  12:44 PM
Analog / digital watch....
What about checking time with the cell phone?
Ive got about 4 watches (after selling others) that I never wear.
I carry 2 cell phones so I haven't needed a watch in about 5 years
Go to Top of Page
  Previous Topic Discussion Topic Next Topic  
Jump To:
All Things (Safety Oriented) Motorcycle © Master Strategy Group Go To Top Of Page
  This page was generated in 0.54 seconds. Powered By: Snitz Forums 2000 Version 3.4.05