How Things Work - Spring 2018

Some comments on standards. We generally use SI units in physics. To inform you: Mass is measured based on a kilogram (kg) standard. Length (or displacement or position) is based on a meter (m) standard. Time is based on a second (s) standard. How do we get these standards? Length - meter (m) - originally 1 ten-millionth the distance from north pole (of Earth) to equator - then a distance between two fine lines engraved on a platinum-iridium bar - (1960): 1,650,763.73 wavelengths of a particular orange-red light emitted by atoms of Kr-86 in a gas discharge tube - (1983, current standard): the length of path traveled by light during a time interval of 1/299,792,458 seconds That is, the speed of light is 299,792,458 m/s. This is the fastest speed that exists. Why this is is quite a subtle thing. Short answer: the only things that can travel that fast aren't "things" at all, but rather massless electromagnetic radiation. Low-mass things (particles) can travel...

How Things Work Physics  103 Spring 2017 Sean Lally seanplally@gmail.com 412.965.0805 M/W - 326 Smith - 7 - 8:15  PM Office Hours:  30 minutes before class and immediately after class (as late as desired) htwspring2018.blogspot.com How Things Work ,  Louis A. Bloomfield Good evening physics phriends!  Welcome to a new semester and your new favorite class, "How Things Work," with your humble host, Sean Lally. I am thrilled to be sharing some of the big ideas of physics with you this term. There will be 3 non-cumulative exams, equally weighted.  Exams are generally multiple choice, though it is possible that there *may* be short answer questions, mathematical problems or 1-2 paragraph essays asked as well. I will assign problem and question sets regularly, but these will not be collected.  Primarily, they are used to help you study material and see what concepts I find to be most valuable (on exams, and in general).  I will give some ...