Friday, December 08, 2006


Clock enigma

The tips of the faster hands of a big clock and the slower hands of a small clock do indeed move at vastly different speeds from each other. How can two things that move at different speeds be said to keep the same time?

It has to do with the circumference of the clock. The hands on a big clock are 'faster', because they have to cover a greater distance in the same amount of time as a small clock, whose hands will travel a shorter distance.
I cannot see this in any other way than was simply & well explained by bdleaf.

Another example similar to the clock is with tires. A twelve inch tire will show one distance for one revolution, while an eighteen inch tire shows a much greater distance for one revolution. But the eighteen will have to travel at a much greater speed to make one revolution in the same length of time.

If I may throw in another enigma, years ago I read in a book on physics, which I don't remember very well, but will get the point across, the following:

This physicist said if you had a pair of scissors with a regular handle, but with very long blades(I don't remember how long, just very long)& closed them normally, the speed of the cut at the end would be somewhere around the speed of light. This isn't similar to the clocks, but to me a quite bizarre enigma.

If you had a pair of scissors with two foot blades & closed them at a uniform speed, would the speed at the beginning of the cut differ from the end of the cut, & if so, why?
This is not and enigma. Your measuring the passage of time. Not distance. One full rotation equals one unit of time. Period. Be that unit a minute, an hour, or a day.
Time, be it a minute or an hour, is fixed. The hands on the bigger clock have to ramp up their speed to get from point A to point B. The hands on the smaller clock register the same passage of time with less expenditure of energy. There are many analogies one could draw from our human existence.
To anonymous: My scissors enigma is still there. With a short handle & exponentially extended blades, the speed of the cut would begin slow & approach the speed of light. And considering time dialation, something has to happen to time & the blades(matter),beginning at about 90% the speed of light. My question remains, what accelerates the cut to relativistic velocity?

To lee1954: I agree with your comment completly. But I'm not so sure about our site masters. They are far too intelligent & inquisitive to ask such a simplistic question. Just as a "for instance", are they referring to a previous question concerning "is time the same everywhere"?

Or am I making a big deal out of nothing & such a simplistic question was asked?
This is hardly an enigma. A clock is designed with three independently rotating hands that rotate at the exact right speeds for each to travel the full circumference of the clock in either a second, minute or hour. That's why clockwork is used idiomatically to refer to a complex mechanism. Has anyone ever looked at the inside of a watch? You'd see why watchmakers have to be so good at what they do.
Clocks don't measure time, they dictate it.
I think they are exactly same speed. One turn each minute.
they dont keep the same keeps minutes, one seconds and of course the last keeps track of the hours
I guess you could say they keep the same time, but at different resolutions.
Well are aren't living in the exact time on the dot right to the second anyway because who knew or started to actually record what time it was when the world first began, so we could be way off. It doesn't really matter I guess, it's just a way to keep a daily routine and schedule so you know when to get to places. Some days I wish there was no such thin gas time though!
to joa1431
Hi im a fouth dimentional thinker.
the result of the speed of light at the end of the cut, is what causes the tips of scissors to go dull before the rest of the scissor.this is also the same for knives. Burn a piece of paper, in a candle flame.Think of the paper as a whole object, not a pile of chemicals. The paper enters the flame and begins to burn. Burning, is our 3 dimentional comprehension of what is happening to the paper. What is really happening is that the paper is being consumed at the speed of light. because flame is traveling at the speed of light within linear time. the then has no purpose, and this causes also the paper to have no purpose. The result, because the paper has no place to go, the speed of light rips it apart.Some of the paper particles are happy to continue at the speed of light, while some particles fall out, resulting in what we see as ash,in our 3 dimentional world. Makes sence? lol sorry bout my grammer and spelling. Another tidbit, Every atom knows its place in the universe and communicates it at the speed of light.
Like everywhere in life, the little guy is just keeping track of the big guy. You don't need the little guy to tell what time it is. He's just racing around at 12x the speed to make it easier for YOU!
The distance, speed or size is not what's being measured. Time is being measured.

A corralary would be that Martha runs a mile in 5 minutes but it takes Fred 10 minutes. How can both distances be a mile? It sound silly when you use a well known fixed thing like a mile instead of a vague concept like time. But it's the same thought process.

The only enigma here is 'time' itself.
The real enigma is the fact that we think we can measure time at all. How do you measure a dimension? If the universe is expanding at an ever increasing rate, wouldn't that dictate an ever increasing difference in the way time is "measured"? The concept of time, I am sure, is a phenomonon of this planet. Someday when we finally contact the visitors, I believe that we will be set free from this earthly constraint.
It's irrelevant how many centimeters a clock's hands move. It's the angle that is important. The minute hand moves 360 degrees an hour.

You don't read a clock in distance, it's the angle that counts.
We shouldnt think of it "the hands are moving at a certain speed to keep the time."

Think of it more as "the hands are pointing at numbers to keep the time."

It doesnt matter what speed any clock moves, aslong as once a second the 'seconds hand' is pointing at the next number.

Increase distance (larger clock) while time is fixed (one minute), and speed will follow (greater speed)

Not an enigma, just preschool physics...
Oh come on, it's simple.

A traditional clock represents time by the angle between hands. The angles change at the same rate. The speed of the ends of the hands have no more relevance than the colour of the face.
this is so stupid. speed = distance over time. further from point of rotation, greater distance to cover, equally greater speed.

p.s. to "anonymous" at 8:36pm;

i love the concept of "Preschool Physics" :)
Youre right this is n enigma. Remember we are talking about 1 clock hand not 2 hands. If you think of a clock face that is 12miles in circumference, and the hand is travelling at 1mph, then it takes the hand 12hrs to make 1 complete rotation. But if you mark a point on the same hand half way down and measure the distance of its rotation then it only travelling 6 miles for one complete rotation. If its still travelling at 1mph then this means its only taken 6 hrs to make one complete rotation. It helps to imagine 2 runners racing around the clock. One runner on the outter edge and one closer to the center. If the runners race around the clock and finish equal then the runner on the outter edge of the clock must have ran faster than the one closer to the center because he had more distance to cover. But this is not the case if the runners were attached to the clock hand because the hand moves at 1 sec per sec and therefore they are travelling at the same speed. So how can they finsih one complete rotation at the same time?
If Time = Distance divided by speed why doesnt this apply to a clock? Someone please explain
Well, I suppose you could also say that the respective hands have the same rotational velocity, regardless of the size of the clock. 1 rpm in the case of the second hand, 1/60 rpm for the minute hand, and 1/1440 rpm for the hour hand.
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