184_projects:building_hq [Projects & Practices in Physics]

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===== Project: Building Stormchaser HQ =====
You are part of a secret organization that sends task forces to investigate strange phenomenon. The name of your particular task force is S.P.A.R.T.A.N force. Your team has been sent to investigate an abnormal storm system that has encapsulated the town of Lakeview. You and your team are racing to be on the frontline to investigate this new system and as you speed toward Lakeview you receive a call from a group of scientists working at Stormchaser HQ. They explain that they have built their new base of operations (HQ) 2 km away from the mountains, which typically gather large clouds (on average, $m=1*10^9 kg$  and $q=-150 C$) to the west of the HQ. The Lakeview scientists have calibrated the equipment on top of HQ to deal with the electric potential from the large clouds, but they are concerned about an incoming storm system that is displaying abnormal qualities. As much as they would love to collect data on this storm, if the electric potential changes by more 20 MV due to the additional clouds, the equipment will be damaged. They have received reports that the storm system is heading toward HQ from the eastern plains (where the wind can last up to 20 minutes and exert a force of 36000 N) with a mass around $m=3*10^5 kg$  and a charge between $-50 C$ and $-60 C$. (For out-of-town-ers, they like to clarify that the eastern plains are roughly 500 km away.) They know that you need immediate data on the storm and would like a recommendation from your team on whether they can keep their equipment on top of HQ or if they should take it down for this storm.
<WRAP INFO>

===Learning Goals:===
  * Understand how electric force, electric energy, electric potential, and electric field relate to one another (and be able to calculate these quantities for a system of point charges)
  * Apply energy principles to a situation with charges (energy conservation, transfer of energy, system definitions, etc.)
  * Apply momentum/force principles to a situation with charges (momentum-force relationship, force-acceleration relationship, force diagrams, etc.)
  * Think about what might change when there are multiple sources of charge in the problem
</WRAP> 

Conceptual Questions
  - How do you find the total electric potential when there are 2 charges present?
  - What assumptions did you need to make to simplify this problem? (There are a lot of them!) Why did you need to make each assumption?
  - What tools did you use from physics 1 to be able to solve this problem?
  - What is the difference between electric force and electric field?
  - What is the difference between electric potential energy and electric potential?
  - What is the difference between electric force and electric potential energy?
  - What is the difference between electric field and electric potential?
  - How would you find the electric potential or electric field if 2 (or more) charges are present?