olympiaddict wrote:Just a few quick questions
The final task says to switch on a light, but I don't see where it allows electric lights. Unless photocell includes electric lights, but I thought that only referred to photoresistors like CdS cells and photovoltaic (solar) panels. Is my definition of photocell correct / can anyone clear this up for me? Thanks
I like the rules this year although the size element is tricky
olympiaddict wrote:Great, thanks
Also, I'm a little unsure of what constitutes an energy transfer with regard to a whole bunch of things happening in a very related and causal way. Like, for example, a battery lighting a rocket igniter which lights a candle and heats something else.
Does that count as
Chemical -> electric -> thermal -> chemical -> thermal?
Would a switch closing a circuit to power a lightbulb count as
Mechanical -> Electromagnetic spectrum or would it be mechanical -> chemical -> electric -> electromagnetic spectrum
Olympiaddict, in general you should consider every change of energy form that occurs as the chain of actions in your machine proceeds. There are, however, two exceptions to this of which I am aware. One is spelled out in rule 3e. - when the rocket igniter is activated, it produces both light and heat, but in your first example, it is the heat which lights the candle, so your TSL should ignore the light that is produced. The second exception is one of the unwritten rules of Mission Possible - the black box rule. This says that what happens inside a component that you did not construct yourself does not count as a transfer. For example, the chemical reaction inside the battery is ignored, and it counts as electrical only. Likewise, the candle is a black box that takes heat from the ingiter as an input and produces heat (and light) as an output. So I'd say electrical >> thermal>>thermal, which heats the "something else. On the other hand, if you replaced the candle with a wad of cotton string (not a black box), I'd accept a chemical transfer for the oxidation of the string between the two thermal steps.
For your second example, the bulb is a black box which changes electricity to light (or maybe heat), so I'd say mechanical>>electrical>>electromagnetic (or thermal). In this case the thermal step of the electrical current heating the bulb's filament does not count, since it is "inside the box."
gorf250 wrote:Is this "blackbox" rule a legitamate rule the event supervisors will uphold, if it is not written anywhere in the rules? If so would something such as motor not count either? I've never done this event C div before but that seems to limit the event quite a bit.
twototwenty wrote:Also, a quick question of my own: do you all think using a mechanical force to close a switch would actually be a mechanical-to-electrical conversion? Because the energy for the electricity is still coming from the battery, not the switch being closed.
Also, a quick question of my own: do you all think using a mechanical force to close a switch would actually be a mechanical-to-electrical conversion? Because the energy for the electricity is still coming from the battery, not the switch being closed.
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