Project: Protecting the Lab
Kick Off Questions
- What is the difference between electric force, electric field, electric potential, and electric potential energy?
- How would you find the electric potential or electric field if 2 (or more) charges are present?
- If an object has no net force, does that mean the object is at rest?
- What do you remember from Physics 1 (or previous science courses) about energy conservation?
Main Problem
As you return from your meeting with Mayor Rachel, you receive a call from your support team working at Stormchaser HQ. S.P.A.R.T.A.N. has a secret research facility called the Facility for Transformative Observations of Electromagnetism (FTOE) outside of Lakeview, at a site protected by mountainous terrain on one side. Your team explains that they built FTOE 2 km to the east of the mountains, which typically gather large stationary clouds (on average, $m=1 \times 10^9$ kg and $q=-150$ C). They have equipment on the roof of FTOE to take data on the abnormal storm clouds. The equipment is 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 an incoming cloud with a mass around $m=3 \times 10^5$ kg and a charge between $-50$ C and $-60$ C is heading toward FTOE 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.
Your team knows that you need immediate data on the storm to understand what's going on, but the equipment can't be replaced with all of the lightning strikes. They need a recommendation from you on whether they can keep their equipment on top of FTOE 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
Wrap Up Questions
- What tools did you use from physics 1 to be able to solve this problem?
- 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?
- How reasonable were the assumptions that you made? How accurate is this model?