l2p - Today Announcements: HW#1 is due Wednesday by 8:00 am...

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ISP209s8 Lecture 2 -1- Today • Announcements: – HW#1 is due Wednesday by 8:00 am – The first extra credit assignment is on the LONCAPA system. One short answer is all that is required. The due date is 23 January at 8:00 am. •R e v i ew • Units • Motion • Scalars, Vectors, Tensors ISP209s8 Lecture 2 -2- Review Time is the thing that is measured by clocks What we know about the laws of nature say the speed of light is a constant , independent of the speed of the source. – One of the implications is that moving clocks run slow – Time is relative Position – location relative to the center of a coordinate system (0,0) Velocity – rate of change of position Acceleration – rate of change of velocity • Distance = speed x time ( 60 mi = 60 mph x 1 hr) ISP209s8 Lecture 2 -3- Time Travel • Moving at high speed is a way to travel into the future. No problem here; this is correct. • We can look into the past because, although the speed of light is fast, distances in space are large. – We see the Sun as it was 8 minutes ago – We see nearby stars as they were 4-10 years ago – The distance light travels in one year is called a light-year. – We see nearby galaxies as they were 1 million years ago – Looking out at the stars is like looking back in time. • We can move forward in time. Can we move backward in time? Maybe ISP209s8 Lecture 2 -4-

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l2p - Today Announcements: HW#1 is due Wednesday by 8:00 am...

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