Analog and Digital Time

Date: 11/15/2004 at 01:02:00
From: natalie
Subject: what is analog time

What is 4:05 in analog time?  I don't get what analog time is.  Is it
something like 24 hours?  Or is it something else?

Date: 11/15/2004 at 14:41:08
From: Doctor Peterson
Subject: Re: what is analog time

Hi, Natalie.

Numbers can be represented in either analog or digital form.  "Analog" 
means that we are making an analogy between the number and some 
quantity we can sense, such as a position on a graph or the angle of a 
needle on a gauge.  "Digital" means that we are showing a numerical 
form (digits), that you have to read.  

For example, on older cars, the speedometer is analog (a needle whose
position represents the speed), while the odometer is digital (numbers
click into place to show how far you have driven).  Some new cars have 
digital speedometer and odometer, both shown electronically.

Each type is useful in a different way.  Analog representation makes 
it easy to see how large a number is at a glance; digital 
representation tells you the exact number, as closely as the 
instrument can determine, so you can more easily write down the value.

Old clocks are analog: they show the time by the positions of the 
hands, so that you can quickly see when it is getting close to a 
certain time.  Many new clocks are digital, showing "4:05" (or 
whatever time it is) directly so you can say it or write it down, but 
may have to think a bit to decide how close it is to 3:55.  (Until 
digital clocks were invented, we never called analog clocks analog; we 
just called them clocks!)

So you are being asked to show what position the hands of an old-style 
clock would be in at that time.

If you have any further questions, feel free to write back.


- Doctor Peterson, The Math Forum
  http://mathforum.org/dr.math/