1 PHY093 Physics 1 Introduction

2 Physics (Giancoli)  The most basic of the sciences  Deals with behavior and structure of matter  Usually divided into  (a) classical physics: motion, fluids, heat, sound, light, electricity and magnetism  (b) modern physics: relativity, atomic structure, condensed matter, nuclear physics, elementary particles and astrophysics

3 Why study physics? (Giambatista et al.)  Since physics describes matter and its basic interactions, all natural sciences are build on a foundation of the laws of physics.  In today’s technological world, many important devices can be understood correctly with the knowledge of the underlying physics.

4 Light interference produces shimmering blue color of a butterfly

5 CAT scan

6 How a CD is read.

7 Fiber optics carry signals efficiently based on the principle of total internal reflection

8 Why study physics?  By studying physics, you acquire skills that are useful in other disciplines.  Society’s resources are limited, so it is important to use them in beneficial ways and not squander them on scientifically impossible projects.  By studying physics, we hope that you develop a sense of beauty of the fundamental laws governing the universe.

9 The nature of physics (Cutnell & Johnson)  The science of physics has developed out of the efforts of men and women to explain our physical environment.  The exciting feature of physics is its capacity for predicting how nature will behave in one situation on the basis of experimental data obtained in another situation. Such predictions place physics at the heart of modern technology.

10 Length or distances studied in physics (order of magnitude)  Radius of proton or neutron m  Atom m  Virus m  Height of Mount Everest 10 4 m  Earth diameter 10 7 m  Sun diameter 10 9 m  Distance earth to sun m  Farthest galaxy visible m

11 Some masses (approx.)  Electron kg  Proton / neutron kg  DNA molecule kg  Mosquito10 -5 kg  Person10 2 kg  Ship10 8 kg  Earth6 x kg  Sun2 x kg  Galaxy10 41 kg

12 Some time intervals (approx.) Lifetime of very unstable sub-atomic particle s Lifetime of muon s Time between human heartbeats 10 0 s (1s) One year 3 x 10 7 s Human lifespan 2 x 10 9 s Life of earth s Age of universe s