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PHYSICS 101 ( Physics for the Nonscientist)

PHYSICS 101 ( Physics for the Nonscientist). Dr. Anatoli Frishman frishman@iastate.edu. Web Page: http://course.physastro.iastate.edu/phys101/. Introduction. What is physics? A science A basic science The most basic science Discovered by several generations of scientists

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PHYSICS 101 ( Physics for the Nonscientist)

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  1. PHYSICS 101 (Physics for the Nonscientist) Dr. Anatoli Frishman frishman@iastate.edu Web Page: http://course.physastro.iastate.edu/phys101/

  2. Introduction • What is physics? • A science • A basic science • The most basic science • Discovered by several generations of scientists • Physics and measurements • Relationships between experiments and theory • Mathematics - language of science Course organization • Lectures • Homework • Exams (multiple choice) • two midterm exams and a comprehensive final exam • Formula sheet • Syllabus

  3. Physical quantities, units and standards What do we measure? - Physical quantities. Units- a unit is a measure of the quantity that is defined to be exactly 1. Examples: meter, mile, gram, kilogram. Standard- a reference to which all the other examples of the quantity are compared. Base quantities, and their standards. The International System of Units (metric system)

  4. Other systems of units • CGSE System of Units (metric system): centimeter, gram, second 1m = 100cm 1kg = 1000g • British engineering system This system has force instead of mass as one of its basic quantities, which are feet, pounds, and seconds. 1 m = 3.281 ft; 1 inch = 2.54 cm 1 kg = 0.06585 slug (Not the same as weight!) on Earth 1 kg weighs 2.205 lb, on the Moon 1 kg weighs 0.368 lb

  5. Conversion of units: Multiply by the appropriate representation of 1 to cancel the unwanted units away Converting between metric units is easy, as it only involves powers of 10. Example 1: Convert 3kg into gram Multiples of Units Example 2: Convert 10 mph into m/s

  6. Measurements and uncertainty When we measure something, there’s a limited accuracy: result  error (or accuracy) Example 1: 2.35  0.01 Example 2: Wrong: 2.35  0.1 Correct: 2.4  0.1 Significant figures Example 1: 0.24630 1sf 0.2 2sf 0.25 3sf 0.246 4sf 0.2463 5sf 0.24630 Example 2: Not so clear in some cases: 200 (1,2,3 ?) Scientific notation is crystal clear: 2  102 (or 0.2  103) 1sf 2.0  102 (or 0.20  103) 2sf 2.00  102 (or 0.200  103) 3sf

  7. Physics Electromagnetism Optics Atoms & particles Mechanics Thermal properties • Geometrical optics • Wave optics • Electrostatic • Electric current • Magnetism Condensed Mater High energy Biophysics Classical physics Quantum physics Relativistic physics Quantum relativistic physics

  8. MECHANICS KINEMATICS Kinematics is the study of motion, without the investigation of the cause of the motion 1. Motion • Motion of what? Material point (An object with an irrelevant dimension for the purposes of a particular problem) • Development of models Example: linear motion versus rotational • Motion is relative to the object of reference Examples: the motion of an airplane passenger relative to the airplane, or the motion of an airplane passenger relative to the ground.

  9. 2. One dimensional (1D) uniform motion (Motion along a straight line with a constant speed) Example: Speed: Distance:

  10. 3. Speed a) Average speed: (total distance over total time) Definition: b) Instantaneous speed: Definition: Question: If the average speed is non-zero over some time interval, does this mean that the instantaneous speed is never zero during the same interval? A) Yes B) No C) It depends

  11. Example 1 B Given: A Formula used: Solution: Answer:

  12. Example 2 Given: Formula used: Solution: Answer:

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