184_projects:power_everything [Projects & Practices in Physics]

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==== Project: Power Is Everything ====

The Artemis 13 was able to turn on its boosters and move the craft towards home. Since power is in short supply, several non-vital systems were shut down. However, to successfully go through the landing sequence they MUST turn on the guidance computer system (CS), Environmental Control Systems (ECS), Communications Relay (CR), the warm-up control for the primers for the parachutes (PP), and the Command Control Module (CCM), as well as a floodlight (FL) in the cockpit using only the main battery (230 V). 

Your team on the ground has been working in a simulator to figure out how to turn on each of the systems in various orders, but keeps running into problems. If the total current from the main battery on board exceeds 0.35 A, the battery will die and the Artemis will lose power before it can return safely to Earth. Your flight expert has sent over the most recent steps he has tried and the data they collected for each step. 

  - Turn on only the CR, which seems to work properly and only draws 0.242 A from the battery.
  - Then turn on the PP, which decreases the current from the battery. The CR seems to barely be functioning so you conclude that it is running at it's minimum power of 18.35 W.
  - Next they turned everything off, and switched on only the PP and the FL. Immediately the warning light goes off in the simulator because the current from the battery is way too high at 1.48 A and the flood light has burnt out because the power in the bulb was 264.6 W (exceeding their maximum power rating of 120 W).
  - You decide to start over and turn everything off again. You turn on the CS, ECS, and CCM - which seems to be perfectly alright. The current from the battery is maintaining at a nice and safe 0.188 A. Since this combination works well, you grab the hand-dandy multimeter and find that the CS, ECS, and CCM have the same current but that the CS is using the most power (17.7 W) and the ECS is using the least (10.6 W).
  - Just to try one more thing, they turn everything off and then turn on only the PP and the CS. You find that, even though they have the same voltage, the current going through these elements are different.
 
Mission Control wants to try to turn everything on at once as it is currently configured. They are running out of time and need to get something to the Artemis. Will the current configuration of these elements in a circuit allow the Artemis 13 to get home safely??

<WRAP info>
=== Learning Goals ===
  * Design/draw a circuit that meets given criteria 
  * Use resistor combination rules, loop rule, and node rule to determine the circuit set up.
  * Calculate the equivalent resistance of a circuit.
</WRAP>

Conceptual Questions:
  - What physics principle is the loop rule based? What physics principle is the node rule based on?
  - Are there other solutions that could meet the criteria? Draw them out.
  - What assumptions did you need to make in this problem?
  - Why could reuse resistance numbers between the different steps? Why could you not reuse the current or voltage values?
  - If resistors are combined in series does that increase or decrease the total resistance? What about parallel resistors?
  - How would you evaluation your solution in this problem? (Look at the project rubric.)
  - How would you evaluate the model in this problem? (Look at the project rubric.)