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me n my partner have made a device with a marble and a circular track but we also have an idea to make some kind of hourglass
which idea do u think would be most accurate?

A marble, since you can measure time more "precisely", though the pendulum idea is much better, in my opinion. Please refer to previously posted pages.

any ideas on the best length for a pendulum period? because if the period is longer you could estimate to quarters where for smaller periods you may only get halves

alrite, does anyone know if we can use gears that we buy separately that are meant for toy cars or something to make an oscillating system? because building gears just seems outta question.....lol

Jazzy09 wrote:any ideas on the best length for a pendulum period? because if the period is longer you could estimate to quarters where for smaller periods you may only get halves

One problem is that the pendulum spends longer at the outside (top) of its swing than at the inside, so theoretically you shouldn't be able to estimate in quarters of periods anyway.

qhhsscioly wrote:alrite, does anyone know if we can use gears that we buy separately that are meant for toy cars or something to make an oscillating system? because building gears just seems outta question.....lol

I'm pretty sure that buying gears is OK. We're just not allowed to buy a "counting device" so as long as you don't buy a premade clock that already makes ticking sounds or tells you the time in any way besides YOU actually measuring it, you should be fine. What are you thinking about making with gears?

kmeister87 wrote:

Jazzy09 wrote:any ideas on the best length for a pendulum period? because if the period is longer you could estimate to quarters where for smaller periods you may only get halves

One problem is that the pendulum spends longer at the outside (top) of its swing than at the inside, so theoretically you shouldn't be able to estimate in quarters of periods anyway.

There are ways to get around the longer time on the outside: just accomodate it, don't change it. Plus the period changes over time.

Jazzy09 wrote:any ideas on the best length for a pendulum period? because if the period is longer you could estimate to quarters where for smaller periods you may only get halves

A longer period may be easier to work with since we need to get really exact. However, some event ssupervisors get a little confused about the size regulations. The clock has to fit into the 80cm cube in pieces, not while running, but some coordinators think it has to fit intact, in which case, there is some explaining involved. But this shouldn't be a big issue.

saturnian wrote:

Jazzy09 wrote:any ideas on the best length for a pendulum period? because if the period is longer you could estimate to quarters where for smaller periods you may only get halves

A longer period may be easier to work with since we need to get really exact. However, some event ssupervisors get a little confused about the size regulations. The clock has to fit into the 80cm cube in pieces, not while running, but some coordinators think it has to fit intact, in which case, there is some explaining involved. But this shouldn't be a big issue.

While I think you are reading the rules correctly, you should get specific clarification on that from the person running your particular competition. The rules do not specify any limit on the size of the running device, but obviously there must be some limit, and since the rules are silent that means the supervisor will have to make it up on the spot. The easiest thing for him to do would be to say 80 cm, so if you want yours to expand you should get specific clearance in advance.

Ah, but it's a 80 cm cube. This means that diagonally, you really have quite a bit more than that--just about 138.564cm. That is how long your device can be, if a judge is going to go with the "it must fit intact" fake-rule-thingy.