184_projects:f21_project_7 [Projects & Practices in Physics]

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~~NOTOC~~

===== Project 7 =====
==== Project 7A: Design a Defib ====
The Artemis 13 is on it's way back to Earth and currently is hanging in lower Earth orbit. You and a team of scientists have been desperately re-wiring the spacecraft circuitry to get home. While soldering wires, your android co-pilot Johnny 5 begins to malfunction, it is essential that Johnny 5 not lose all power as he controls the landing sequence to reach the planet's surface. Melissa Lewis, the team leader, mentioned that in a [[https://www.youtube.com/watch?v=H-vXydxLZMk|training video]] she saw back in the 80's call "Short Circuit 2" a model like Johnny 5 was brought back to life using a defibrillator. 

You run to the medical bay and grab the defibrillator and rush back to Johnny 5. When you go to charge the defibrillator, however, you notice that the instruments are not reporting a proper charge. In order to not risk the safety of Johnny 5 by shocking him with faulty equipment, you decide against pressing the button and shouting "clear." You need to save Johnny 5. Using your knowledge of electromagnetism, you know you can create a makeshift piece of equipment to be able to stabilize Johnny 5.

You run to the limited "stock room" on board, only to discover limited supplies. You manage to find sheets of aluminum, and various paper sheets, some electrical tape and wires, and a pair of all-purpose scissors. 

The defibrillator must be able to deliver 360 J to Johnny 5 in order to stabilize him. Can you fix the instrument and save him?

The paper sheets are 0.5 m wide, 2 m in length, and vary in thickness (2 mm, 1 mm, 500 $\mu$m, 50 $\mu$m, 1 $\mu$m, 0.5 $\mu$m). The aluminum sheets are 0.80 m in length, 0.5 m wide, and 0.3 mm in thickness. The defibrillator has a high voltage power supply of 30 kV.

<WRAP info>
=== Learning Goals/Conceptual Questions ===
  * Explain how a capacitor charges and discharges
  * Draw V vs t, Q vs t, and I vs t graphs for both charging and discharging circuits.
  * Explain what changes about your capacitor when you have a dielectric
  * Explain why you add a capacitor to a circuit and what would change about the circuit.
  * Explain why you would add a resistor to charging/discharging capacitor circuit.
  * Explain what the difference is between a capacitor that is "initially connected" versus one that has been hooked up for "a long time"
</WRAP>



==== Project 7B: Austin, we have a snafu ====
The Artemis 13 is almost home but before they complete their final landing sequence the team needs to launch a top-secret deep space probe that will be piloted by Johnny 5 into the eye of the storm over Lakeview. However, the power supply for the whole ship is running critically low, so you are now only running the ECS to maintain oxygen in the command module. You have to somehow power up the probe to complete your mission. You no longer have communications with Austin. 

You notice as you begin powering up the probe (which operates on its own reserve power system) that although the navigational controls have been primed, there are several components that are not responding to testing. It appears that the circuit switch control board got fried during the test jump, as a result, you now need to create a new circuit that will allow you to provide different amounts of energy to the propulsion system's module on the probe.

That propulsion system consists of the primary burners and the cooling system, which have a total resistance of 65 $\Omega$.
The primary burners require a short burst of 200 J to power-up.
The cooling system requires a short burst 300 J to power-up.

You need to be able to deliver different amounts of power to this module; however, you are growing concerned that the power supply the probe has access to of 100 V may not be sufficient to power these probe systems. You manage to find some additional batteries onboard (three 10 V batteries from the supply room) to use if you need them. 

You also have several  0.125F capacitors and resistors (1 $\Omega$, 5 $\Omega$, 10 $\Omega$, 50 $\Omega$, 100 $\Omega$) on hand. 
You also have access to multiple switches that can be used to open and close parts of the circuit you are designing.  

There is a breaker in the circuit that is a failsafe and will trip if the current reaches 2 A. You also know that there are delicate circuit elements in the primary burners and the cooling system, so the propulsion system should not be connected to any power supplies when charging capacitors.

You should provide a circuit diagram of your design that helps you explain to your crew that the current in the circuit is safe and that you are going to be able to supply the needed power to the systems when the time comes to launch the probe. As a check for yourself, you should make sure that the voltage in the circuit adds up to the correct amount as to not suffer any voltage shortages.

<WRAP info>
=== Learning Goals ===
  * Understand how capacitors charge and discharge
  * Use the relationship between capacitance and energy
  * Understand what happens when capacitors are in parallel or in series
  * Understand how capacitors and resistors combine in a complex circuit
</WRAP>