Assignment 10

Reading: sections 16.6, 17.3, 17.4 (before Tuesday's class).

Hand in orbits worksheet.

Mastering Physics (you may want to wait until after Tuesday to do the chapter 17 questions)

Written problem:



The year is 2347. Non-stop construction at UBC has long ago filled all useable space on campus, but thanks to the availability of fusion-powered space vehicles, the construction of orbiting classrooms and laboratories has been possible for nearly a century. Rather than continuing to hire new faculty members, UBC decided in the mid 21st century to begin cloning its existing faculty members to ensure a consistent quality of instruction through the centuries.

One day, 7Mark2312 (7th human clone of 2014 Mark, born in the year 2312) is giving a lecture on momentum conservation in the orbiting Science One classroom. To demonstrate that momentum isn’t conserved when the environment of an object is not translationally invariant, 7Mark2312 throws a piece of chalk towards the wall of the classroom. Unfortunately, the chalk hits one of the windows.

Had this been a piece of 21st century chalk, thrown by a 21st century Mark, everything would have been fine. However, in the 24th century, chalk has been reengineered using ultra-hard compounds to last almost forever, be nearly indestructible, and not leave chalky white smears all over your clothing. At the same time, 7Mark2312 has the strength and physical conditioning of an elite athlete, since UBC’s army of cloned professors spend 2-3 hours each day at the gym to develop the physical stamina necessary to teach 12 classes per semester. With the combination of 7Mark2312’s almost super-human throwing abilities and the nearly indestructible nature of 24th century chalk, the window (a cheap, 23rd century model) breaks and the chalk sails right through.

If the chalk leaves a 0.5 square centimeter hole in the window, the classroom is the same size as the current Science One classroom, the air in the classroom has a temperature of 20 degrees Celsius, and the pressure is equal to the standard atmospheric pressure on Earth, approximately how long does it take before 1% of the air molecules leak out of the capsule into space?

 (Hint: think microscopically!)