I have to make a time piece without using electricity.

[square965]

Hi, I am taking part in a science competition in which I must design a device that can measure time. I must measure 5 different lengths of time that range from anywhere from 10 to 300 seconds. The catch is that I am not allowed to use any electricity.

 

I have a few ideas that I'd like to get some opinions on:

 

The first is to set up a pressure-activated piston that would launch a ball onto a platform that would return the ball back onto the piston. I would record the amount of time it took for the ball to be launched each time, and simply count the number of times the ball is launched during the competition.

 

The other idea is to build a series of alternating J shaped ramps, then measure the amount of time it takes for the ball to fall to each new J shape. The problem with this one is I'm not sure how to ensure that acceleration due to gravity doesn't throw off the results.

[Mr Skeptic]

Or, you could use a pendulum. The first clocks used pendulums.

[SH3RL0CK]

How accurate must this be? A sundial would actually be sufficient if accuracy wasn't a concern.

[Martin]

Hi, I am taking part in a science competition in which I must design a device that can measure time. I must measure 5 different lengths of time that range from anywhere from 10 to 300 seconds.

 

Skeptic already mentioned pendulum, the obvious thing that comes immediately to mind.

 

The thing is though, I don't understand how the competition is set up.

Do YOU get to pick the 5 intervals which must all be 10-300 seconds?

 

 

Or do you walk in with your timepiece device and the judges hand you a piece of paper with 5 lengths of time that THEY chose that you weren't told ahead of time and which you now have to measure?

 

Or do they tell you 2 weeks in advance what the 5 intervals of time are going to be which you have to measure?

 

Which is it?

[michel123456]

You can go and google about ancient techniques used before the invention of clocks, such as: candles, sand timers, clepsydra, a.s.o.

[Klaynos]

Water clocks was the first thing that came to my mind.

[npts2020]

A spring with a ratchet mechanism is how most wind-up watches and many clocks work. You could probably even find an alarm clock to get one out of for only a few bucks or less.

[michel123456]

I suppose you can also use other techniques such a chemical reactions, or distortion of a metal under heating (I suppose you can use gas or other power sources except electricity).

I remember also a toy. A metal rod (~30 cm) verticaly inserted into a wooden base. A little wooden bird attached to a wooden sphere by a spring. Something like this:

 

 

When you pull the bird's head once, he begins falling step by step. The nose hits the rod, then go back & release the pressure applied by the wooden sphere. The hole in the sphere is a tiny larger than the rod's section. The tok-tok downward process can last a minute. Very funny (for a dad).

[Martin]

Hi, I am taking part in a science competition in which I must design a device that can measure time. I must measure 5 different lengths of time that range from anywhere from 10 to 300 seconds. .

 

 

The guy still has not told us what the timepieces are being judged on. Is it accuracy or, say, how original and funny they are.

 

He has not told us how the 5 intervals to be measured are to be chosen.

they range from 10 seconds to 5 minutes.

 

Very likely he will have to set the timepiece to run for some interval, like

4 minutes and 25 seconds, say. And then it will have to run by itself without assistance for that whole time. And then stop, or ring a bell---generate some recognizable event signifying the end of the period.

 

That's how I would set up the contest, I think. And screw originality and humor. I would judge on accuracy.

 

Other people might imagine the contest differently.

 

Let's agree on some rules, criteria, format or something. Unless the original poster gets cooperative and obliges us by telling us what they are.

[foodchain]

I thought you might be able to use a rubber band or something else elastic, but for three hundred seconds that would probably involve danger. I think what would be cool is a sort of waterfall if you could get a controlled drip, and that as the water pours down the initial drip could be timed to three hundred seconds. The rest of the time intervals could be process that go on below it, like one that overflows every ten seconds.

 

I Also thought using a force to spin a coin would be cool, but then again no way to predict easily and 300 second spin would probably shoot it through a wall:D

 

Do magnets count as electricity? I dont know what you could do but I am sure some kind of process could be rigged with magnets.

[square965]

Sorry for the late response guys, helping out with school science fair has been keeping me busy. The way it works is the people have a predetermined amount of time in the form of two beeps from a computer or stopwatch. I don't know what this amount of time will be besides it being from 10-300 seconds. I have to estimate the amount of time between the two beeps to the nearest tenths place using my device.

 

edit: oh and human interaction IS allowed throughout.

[npts2020]

How about a water filled container? Figure out a drainage rate in drops per minute and count the number of drops, you should be able to adjust the rate to whatever rate you desire. More drops will be harder to count but more accurate if done right. As long as your reservoir is much greater than the amount of water you use the drainage will have negligible effects on accuracy.

[michel123456]

Accuracy is the challenge.

And calibration of your device.

Not so easy.

 

I guess you'll need an arrow upon an index in order to calibrate, like a regular clock.

Maybe through the variation of level into a bucket of water, not counting the falling drops but with a floating object (a ping-pong ball) attached to a mechanism increasing accuracy, like an asymetric balance, or strings around a wheel. Just an idea.

Edited February 24, 2010 by michel123456

[SH3RL0CK]

How about a water filled container? Figure out a drainage rate in drops per minute and count the number of drops, you should be able to adjust the rate to whatever rate you desire. More drops will be harder to count but more accurate if done right. As long as your reservoir is much greater than the amount of water you use the drainage will have negligible effects on accuracy.

 

Never mind counting the drops, just measure the volume of the water that has drained. That way you only need to take one measurement at one time. You can also calibrate the water volume to account for the slower drip rate once the bucket level has dropped (due to a longer timeframe).

[Martin]

... people have a predetermined amount of time in the form of two beeps from a computer or stopwatch...

edit: oh and human interaction IS allowed throughout.

 

Thanks for the detail. So human interaction is allowed throughout.

That is important. It means you could be sitting there counting pendulum-swings, instead of having to contrive a device to do the counting mechanically, like the notched wheel you see in old clocks.

 

Why don't you right now get a piece of string and a metal weight and see how close you can come to timing seconds?

Adjust the length of the string so each round-trip swing takes one second, and a round-trip takes two seconds.

See how good you can do with just that simple method.

 

The point is that the round-trip swing time is nearly independent of how much swing angle. A wide swing going fast or a narrow modest-size swing going slow---the roundtrip time is always the same. It is what makes it an ideal simple timer.

 

Try timing 15 seconds. Within reason, it should not depend on whether you give it a large nudge to start or a small nudge. What matters is the length of the string. See if you don't find that to be the case. This should take you only a short time to do, and then you will know something by your own direct experiment--instead of just reading or being told.

 

Or make the string longer so that each one-way swing takes one second.

 

I'm not suggesting you use pendulum (weight on a string) for your final project design but I suggest you quickly, in the next half hour, get some experience directly measuring time with a simple device. Pendulums can be very accurate. Just don't let it swing wildly, a moderate angle of swing is good.

Compare it with the second hand of a regular clock and, like, time 15 seconds with 15 swings. Adjust the string length until it is perfect. or nearly perfect. Easy, and good experience.

Edited February 25, 2010 by Martin

[Mr Skeptic]

Yeah, and try to pick something nice and heavy for your pendulum's bob, otherwise air friction will slow it down too much.

[Martin]

Good point. :-D

And pendulum was what you suggested already in post #2.

Whether or not that is the final project, it is valuable experience with a rather accurate simple timing device.

Basically copying what Galileo did in the early 1600s---about 400 years ago. A savvy dude, that we owe a lot to.

 

This source says G experimented with pendulums in 1602

http://cnx.org/content/m11929/

and described the constant swingtime feature in a letter to a friend

also that around then another friend of G's began using a pendulum to time the pulse of medical patients.

But G did not publish his pendulum findings until much later, in the 1630s.

For more, google "galileo pendulum" or check the Wikipedia.

Edited February 25, 2010 by Martin
Consecutive posts merged.

[michel123456]

Pendulum is ok, but it means our friend must be right there all the time counting swings without comitting any mistake. If the experience lasts 5 minutes, it will be painfull & difficult. And there will be no possibility for cross-checking the measurement afterwards.

 

Another problem is accuracy. From the moment the first beep will sound, and the pendulum put in motion, there will be a non negligeable duration. The same at the end of the test. The human intervention will cancel all accuracy. In any case.

 

I was thinking more about water, as Sherlock proposed, but to measure the volume of water is also a problem. You are not permitted to lose any drop. And capillarity may cancel also any accuracy.

Maybe with sand.

If 1 gr of sand is falling in each second, and if 1 gr of sand is made of lets say 1000 particles, you can get accuracy of 1/1000 sec simply by counting the sand one by one. If the experiment lasts too long, you can imagine recipients of standard volume (lets say 10 sec.) in order to avoid counting the entire sand volume. You will have to count only the last one.

By this method, you have a trace of the experiment, and you can have double check by letting someone else counting the sand again.

[mylko]

So did you ever make a non-electric clock? If so, how did it turn out?