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Unformatted text preview: ISP209s10 Lecture 2-1- Today • Announcements: – HW#1 is due Wednesday by 8:00 am – The first LONCAPA extra credit is due 1/27 by 8:00 am. – Register your clickers in LON-CAPA • Review from last time (time dilation, etc.) • Units • Scalars, Vectors and Tensors • Motion and Newton’s Law of Inertia ISP209s10 Lecture 2-2- Overrides and Add-Drops • Override period expired on Friday 1/15 – The final overrides I granted were on Thursday. I could not give anymore since we are technically over the room capacity. – Now the only option is to get an add/drop slip from the ISP office and ask me to sign it. – HOWEVER, I cannot sign this until the enrollment goes down below the room capacity. Check back with me before class on Thursday. – If you are eventually able to get me to sign your add slip, it is your responsibility to do extra credits etc. to compensate for the missed HW #1. – If you want to DROP the course, you can still do this online. ISP209s10 Lecture 2-3- Physics Help Room Hours • TA = Steven Barthelemy Monday: 1pm - 3pm Tuesday: 4pm - 6pm Friday: 1pm-2pm ISP209s10 Lecture 2-4- Review: Einstein’s Postulates 1) Principle of Relativity: Laws of Nature are the same in all non-accelerated (aka “inertial”) reference frames. 2) Principle of the constancy of the Speed of Light: The speed of light in empty space is the same for all non-accelerated (aka “inertial”) reference frames: c = 300,000 km/s From these 2 postulates and nothing more, Einstein’s Special Theory of Relativity follows ISP209s10 Lecture 2-5- Review: Relative Motion with Mort and Velma • Velma rides a train that is going 50 m/s relative to Mort • Velma throws a baseball at a speed 20 m/s (relative to herself ) towards the front of the train From Mort’s perspective, how fast is the baseball going? Ans: 50 + 20 = 70 m/s This is common sense. The velocities of the train and ball add. We call it “Galilean” or “Newtonian” relativity . ISP209s10 Lecture 2-6- Review: Constancy of Lightspeed “c” You might expect Mort measures the speed of Velma’s light beam to be c + .25c = 1.25c. This is NOT the case. They both get c= 300,000 km/s. c = 300,000 km/s !!! ISP209s10 Lecture 2-7- Review: Relativity of Time • Einstein’s simple thought experiment with “light clocks” implied some mind-blowing consequences about Time: – Moving clocks run slow (I.e., Time slows down) – Time is relative according to your reference frame 2 2 2 1 1 1 1 ! " " # = $ $ % & ’ ’ ( ) # = = c v t t time that elapses on your watch time that elapses on the moving watch “Time-Dilation” ISP209s10 Lecture 2-8- Review: Confirmation of Time Dilation • Airplane experiment: A high-precision clock is taken on a long jet ride that circles the Earth several times. An identical clock stays on the ground. When the 2 are compared after the trip, the one that was on the jet is behind (I.e., slower)after the trip, the one that was on the jet is behind (I....
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This note was uploaded on 05/04/2010 for the course ISP 209 taught by Professor Sherrill during the Spring '07 term at Michigan State University.
- Spring '07