# Non mechanical timing device

1. Feb 23, 2005

### k_2_the_arma

I need to design and create some sort of device to measure an interval of time between 10 and 40 seconds. I can't use any electrical or mechanical things. I had ideas of puting water in a funnel and letting it fill up a cup in which I've measured how much water equals a second for example. I also thought of dropping marbles off of a low-incline ramp and timing it's drop to the base. The catch is my physics teacher is making everyone in the class do a different project, the water measuring one has been taken and so have the marbles.
Does anybody have any ideas on what I can do? I have no problem designing, building and testing the device I just need to get going here.

Thanks All

2. Feb 23, 2005

### Tom Mattson

Staff Emeritus
Given that both the water and marble clocks are "mechanical", I am at a total loss. What exactly is ruled out by that term?

3. Feb 23, 2005

### k_2_the_arma

I used the wrong term. We can't use anything electronic appliances such as fans, dremel tools etc.

4. Feb 23, 2005

### Tom Mattson

Staff Emeritus
A-ha. In that case, how about a pendulum? Has that idea been taken?

5. Feb 23, 2005

### k_2_the_arma

well i was considering using a pendulum, but the period is bound to change during a duration of up to 40 seconds - I am allowed only a 2 second grace period

6. Feb 23, 2005

### k_2_the_arma

It's still a possibility to do something involving marbles. One other person is already doing something where they mark on a track every second, and as the marble falls they count how many seconds the marble passes through. A good idea, but unfortunately I can't do the same thing

7. Feb 23, 2005

### brewnog

Sand timer? If sand's taken, how about a sugar timer? Or a salt timer?

8. Feb 23, 2005

### k_2_the_arma

I am always one for cutting corners, but yup somebody is connecting two 2-liter soda bottles and filling it with sand. his friend tried to do sugar and it's not allowed

9. Feb 23, 2005

### arildno

Why do you dismiss pendulums so easily?

You've got other versions than the grandfather clock variety, you know..
Look up, for example, torsional pendulums to get another pendulum type

10. Feb 23, 2005

### k_2_the_arma

a torsional pendulum might work, I'm researching them as we speak

11. Feb 23, 2005

### Tom Mattson

Staff Emeritus
Also, there are other types of harmonic motion: like a mass and spring.

12. Feb 25, 2005

### k_2_the_arma

bump

any

13. Feb 25, 2005

### k_2_the_arma

I came up with another idea that hadn't been taken - it's hanging a slinky from a hanger with a mass on the bottom and letting it stretch vertically, something like in the diagram seen here