course_planning:184_projects:s18_project_15 [Projects & Practices in Physics]

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===== Project 15 =====

==== Project 15: Choose your own adventure ====
Your group is to design a problem that incorporates the main topics that the EMP-Cubed course has focused on:

  - Sources of fields (either electric or magnetic)
  - Superposition of fields (either electric or magnetic)
  - Applications of fields (either circuits and/or an induced voltage/current) 

Your design should include both the **problem statement** (storyline, just look at any of ours for details) and the **solution** to the problem. Imagination is a plus. You should use the four quadrants and include any appropriate sketches (including appropriate measurements and any necessary free-body diagrams). You can write it up on the sheets provided and on the white boards. //Try to include a motivation within the problem for incorporating the main ideas and not just include them randomly//.

A good solution will not just be equations but will include some commentary.

We encourage you to take this opportunity to review any physics you had particular difficulty with. The tutors are here to help you consider the correctness of the physics you are trying to include in your problem.

The winners of the "choose your own adventure problem" will receive the following:

  * A 4.0 grade on the weeks problem.
  * EM Boar Tiger t-shirts for the group.
  * Get to act as TA's on Thursday.

Good Luck!

===== And the winner is... =====

==== Project 15B: Murder in the Mansion ====
One stormy night...Colonel Mustard and Ms. Scarlet were having a dinner date in their ritzy mansion. All of a sudden, there was a scream: SOMEONE MURDERED THE MAID!! Currently, the prime suspects are the other four people that live in the mansion: Professor Plum, Mrs. White, Mr. Green, and Mrs. Peacock. It is up to you to check the validity of their alibis. 

__Mr. Green's Alibi:__ \\
"I was trying to watch the season finale of The Bachelor, but the storm was messing with the satellite. I was on the roof trying to fix the satellite with my wrench, but I got struck with lightning and was passed out for a few hours on the roof."

With some proper sleuthing and detective work, you know:
  * Mr. Green's claimed location was $\langle 0, 16, 0 \rangle$ m.
  * The storm in question was comprised of three clouds:
    * $Q_1 = -500 C$, location $\langle 100, 2000, 0 \rangle$ m. 
    * $Q_2 = -500 C$, location $\langle 0, 2000, 0 \rangle$ m. 
    * $Q_3 = -500 C$, location $\langle -100, 2000, 0 \rangle$ m. 
  * It is plausible that Mr. Green was struck by lightning if the electric field is greater than 3 MV/m. 

__Mrs. Peacock's Alibi:__ \\
"I was on my way home from the store on my electric scooter, but I got stranded a few miles away because the voltage on my battery was too low."

You look up the circuit diagram of her scooter, which simplifies to the circuit below. In the manual, you learn that the battery must have a voltage of at least 20 V to work. 

{{ 184_notes:PeacockCircuit.png?300 }}   

__Professor Plum's Alibi:__
"I was standing on the roof trying to get the perfect dramatic selfie with the storm as a background. When the lightning hit Mr. Green, my phone was thrown upward by the magnetic field, and it fell over the edge of the building. I spent the next couple of hours searching through the weeds to find my phone."

Since this sounded a little sketchy, you drew up the following diagram, which shows the direction of current from the lightning bolt, Professor Plum's location, the current direction in the phone while selfie-taking, and the claimed trajectory of the phone. (Could the force on the phone from the lightning bolt make this trajectory?) 

{{  184_notes:roof.png?500 }} 

__Mrs. White's Alibi:__
"I was on a walk when the storm hit, so I tried to call my husband to come pick me up. However, the electric potential from the storm caused problems my cell phone - it didn't work! It took me forever to walk home."

After further questioning, Mrs. White claimed to have been 2000 m away (in the -x direction) from the mansion. You consult with the cell carrier who tell you that only electric potentials bigger than 5 GV would affect a cell signal.