Message to the Physics Community, Saturday, May 9, 2020

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Dear Physics Community,

Reminder: Mother’s Day is tomorrow!

Even harder – staying inside and keeping a physical distance is hard.  Imagine if you did not have internet access.

No Academic Continuity Meeting today

Physics Department

Lab work – here are some physics problems related to keeping safe in the lab once we return.  A lab is 50 m^2 in floor area and 3 m in height.  Two people are working in the lab, each respires 15 times per minute and, when exhaling, ejects 1000 aerosol particles of 1 um diameter.  Their lung capacity is 3 liters.  Assume the HVAC is off for the first three parts of the problem.

  1. How long does it take an aerosol particle to reach the floor?
  2. Assume each particle remains airborne for a time long compared to any other time in the problem and the air in the room is well mixed.  What is the particle concentration as a function of time?
  3. How many aerosol particles per second does the other person inhale?
  4. The HVAC is now turned on and exchanges the air 10 times per hour.  What is the steady-state aerosol particle concentration and what is the characteristic time for a room initially aerosol free to reach the steady-state concentration?
  5. How many aerosol particles does the other person in the room inhale per second?
  6. Surgical masks capture 20-50% of aerosol particles on exhale.  How does this change the aerosol concentration in the room?  Repeat for N95 faceplate masks that catch 90-99% of aerosol particles.

Quantum cook – in all the shuffle, I missed this MIT News article about Joe Checkelsky, an actual quantum “cook” of novel materials.  Joe made a material that has high conduction when a magnetic field is applied in a precise direction, allowing tuning of the material’s internal energy levels.  Paper here, Science Perspective here.

Los Endos

Northeastern will reopen its campus in the Fall.

Opening today: ‘Spaceship Earth’: They boldly went where none had gone – a sealed dome in the Arizona desert. Trailer here. Family wanted to watch Rushmore instead, which was an excellent choice.

Peter

P.S. I am posting these messages in my blog roll here. Thanks to Physics Council, Pablo Jarillo-Herrero, Cathy Modica, Vicky Metternich, and Christina Andujar for input and comments on these messages.