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Project: Protecting Stormchaser HQ
As you return from your meeting with the Mayor, you receive a call from your support team working at Stormchaser HQ. They explain that they built their new base of operations (Stormchaser 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. They have equipment on the roof of HQ to take data on the abnormal storm clouds. It's shielded to protect it from the electric potential from the large clouds that are usually present, but they are concerned about another 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 a large cloud with a mass around $m=3*10^5$ kg and a charge between $-50$ C and $-60$ C is heading toward HQ from the eastern plains (where the wind can last up to 20 minutes and exert a force of 36000 N). Since you're from out of town, they clarify that the eastern plains are roughly 500 km away.
They know that you need immediate data on the storm to understand what's going on, but their equipment can't be replaced with all of the lightning strikes. They need a recommendation from your team on whether they can keep their equipment on top of HQ or if they should take it down to protect it from this storm.
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
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?