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Mission Possible C

Posted: August 7th, 2013, 7:42 am
by Jim_R

Re: Mission Possible C

Posted: September 4th, 2013, 7:51 pm
by XJcwolfyX
Very interesting topic this year.

Re: Mission Possible C

Posted: September 6th, 2013, 6:05 pm
by olympiaddict
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

Re: Mission Possible C

Posted: September 6th, 2013, 7:17 pm
by iwonder
I think we've all got questions veto similar to that (I'm trying to figure out how to use electromagnetic energy with those restrictions), so I think that we'll need to wait until the national clarifications open to get official word on anything.

Re: Mission Possible C

Posted: September 7th, 2013, 5:56 am
by chalker
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

Unofficially of course, I think this was just a minor oversight. Of course we intend to allow you to use things like LEDs and lightbulbs.

Re: Mission Possible C

Posted: September 7th, 2013, 7:37 am
by olympiaddict
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

Thanks!

Re: Mission Possible C

Posted: September 9th, 2013, 3:14 pm
by torqueburner
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

Thanks!
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."

Re: Mission Possible C

Posted: September 9th, 2013, 4:13 pm
by olympiaddict
Ahah, the black box rule makes sense. I guess my confusion lay in where to "draw the line" perhaps, but thinking about it that way makes it a lot clearer. Thanks

Re: Mission Possible C

Posted: September 9th, 2013, 8:25 pm
by gorf250

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."
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.
In addition, can anyone clarify to me the meaning of a transfer? I interpreted it as an actual conversion of energy, ex. generating a current using a small generator/motor, but the resources my coach gave me listed things like flipping a switch as mechanical to electrical. I see this more as a trigger as the mechanical energy is not transferred to electrical. Am I misinterpreting the rules?

Re: Mission Possible C

Posted: September 9th, 2013, 8:43 pm
by iwonder
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.
No, the blackbox rule isn't written anywhere in the rules. There's no guarantee anyone will accept it. That being said, it's more of a common sense thing that you shouldn't be allowed to count transfers you didn't make. If there's any question at all I'd submit a clarification to NSO when the system opens.