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Physics : Mechanics

Physics : Mechanics. Ahmad Fauzi UNS Physics Education Department Phone 0856 4725 6315 Email: fauziuns@gmail.com or fauzi_uns@yahoo.com Blog: fauziuns03.wordpress.com or fauziuns79.wordpress.com. Materials. Chap.1 Physics and Measurement Chap. 2 Motion in One Dimension

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Physics : Mechanics

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  1. Physics : Mechanics Ahmad Fauzi UNS Physics Education Department Phone 0856 4725 6315 Email: fauziuns@gmail.com or fauzi_uns@yahoo.com Blog: fauziuns03.wordpress.com or fauziuns79.wordpress.com

  2. Materials • Chap.1 Physics and Measurement • Chap. 2 Motion in One Dimension • Chap. 3 Vectors • Chap. 4 Motion in Two Dimensions • Chap.5 The Laws of Motion • Chap.6 Circular Motion and Other Applications of Newton's Laws • Chap.7 Fluid Mechanics • Chap.8 Oscillatory Motion

  3. Course Information: Instructor • Instructor: Ahmad Fauzi, M.Pd. • Office: the 2nd floor of D building • Telephone: 0856 47256 315 • Email: fauziuns@gmail.com or fauzi_uns@yahoo.com • Blog: fauziuns03.wordpress.com or fauziuns79.wordpress.com

  4. Materials Textbook • Raymond A. Serway and John W. Jewett.2004. Physics for Scientists and Engineers.USA: Thomson Brooks/Cole. • Resnick,R and Halliday, D.1997. Fundamental Physics. John Wiley & Sons, Inc. • Tipler. Physics for Scientists and Engineers. • Hewitt. 1993. Conceptual Physics.New York: Harper Collins College Publisher.

  5. What is “Physics” and Why study “Physics” ??? • Physics is concerned with the descriptionandunderstanding of nature (physical world) in an objectiveway. • Measurement is one of its important tools.

  6. nature (physical world) Physical world here refer to phenomena or events, and can be classified into few categories: • Mechanics • Heat • Electricity • Magnetism • Waves and Optic • Quantum • and ….. Etc.

  7. Mechanics • Physics • Kinematics and Dynamics

  8. Electricity and Magnetism • Physics • Electricity and Magnetism

  9. Light and Optics • Physics • Light

  10. Thermodynamics • Physics • Thermodynamics

  11. PHYSICAL QUANTITIES • Nature (physical world) • Mechanics • Heat • Waves and Optic • Quantum … and etc. • Description • Model, • Theories • Laws, • Equations Physics Objectiveway, Physical quantities Quantities Measurements

  12. PHYSICAL QUANTITIES Quantities Measurements Instruments Units Scalar Quantities Vector Quantities Accuracy & Uncertainty Dimension Analysis Significant Figures

  13. Measurements-The Uncertainty Accuracy and Precision: The only kind of physical quantity that can be measured with complete accuracy would occur in simple counting operations, such as I have 25Bahts and 13 Sattangs, or I see two dogs. In physics, as in other sciences, quantities such as length, mass, volume and density of objects often have many different values. ACCURACYand PRECISION are terms that are often used in regard to a measured quantity.

  14. Measurements- The Uncertainty Accuracy and Precision: ACCURACY is concerned with how close a measurement comes to the accepted or true value. PRECISION is the agreement between the numerical values of two or more measurements that have been made in the same way Precise measurements are not always necessary to be accurate.

  15. Physics and Measurement • \Physics deals with the nature and properties of matter and energy.Common language is mathematics. Physics is based on experimental observations and quantitative measurements. • Mechanics deals with the motion and equilibrium of material bodies and the action of forces. • Classical Mechanics: Theory that predicts qualitatively & quantitatively the results of experiments for objects that are NOT • Too small: atoms and subatomic particles – Quantum Mechanics • Too fast: objects close to the speed of light – Special Relativity • Too dense: black holes, the early Universe – General Relativity • Classical mechanics deals with a lot of our daily life objects!

  16. Measurement • Being quantitative in Physics requires measurements. • How tall is Ming Yao? How about his weight? • Height: 2.29 m (7 ft 6 in) • Weight: 141 kg (310 lb) • Number + Unit • “thickness is 10.” has no physical meaning. • Both numbers and units are necessary for any meaningful physical measurement.

  17. Type Quantities • Many things can be measured: distance, speed, energy, time, force …… • These are related to one another: speed = distance/ time • Choose three basic quantities: • LENGTH • MASS • TIME • Define other units in terms of these.

  18. SI Unit for 3 Basic Quantities • Many possible choices for units of Length, Mass, Time (e.g. Yao is 2.29 m or 7 ft 6 in) • In 1960, standards bodies control and define Système Internationale (SI) unit as, • LENGTH: Meter • MASS: Kilogram • TIME: Second

  19. SI Length Unit: Meter • French Revolution Definition, 1792 • 1 Meter = XY/10,000,000 • 1 Meter = about 3.28 ft • 1 km = 1000 m, 1 cm = 1/100 m, 1 mm = 1/1000 m • Current Definition of 1 Meter: the distance traveled by light in vacuum during a time of 1/299,792,458 second.

  20. SI Time Unit: Second • 1 Second is defined as “atomic clock”– time taken 9,192,631,700 oscillations of the light emitted by a 133Cs atom. • Defining unit precisely is a science (important for, for example, GPS): • This clock will neither gain nor lose a second in 20 million years.

  21. SI Mass Unit: Kilogram • 1 Kilogram – the mass of a specific platinum-iridium alloy kept at International Bureau of Weights and Measures near Paris. • Copies are kept in all other countries. • Yao Ming is 141 kg, equivalent to weight of 141 pieces of the alloy cylinder.

  22. Length, Mass, Time

  23. Prefixes for SI Units • 3,000 m = 3  1,000 m = 3  103 m = 3 km • 1,000,000,000 = 109 = 1G • 1,000,000 = 106 = 1M • 1,000 = 103 = 1k • 141 kg = ? g • 1 GB = ? Byte = ? MB

  24. Prefixes for SI Units • 0.003 s = 3  0.001 s = 3  10-3 s = 3 ms • 0.01 = 10-2 = centi • 0.001 = 10-3 = milli • 0.000 001 = 10-6 = micro • 0.000 000 001 = 10-9 = nano • 0.000 000 000 001 = 10-12 = pico = p • 3 cm = ? m = ? mm

  25. Derived Quantities and Units • Multiply and divide units just like numbers • Derived quantities: area, speed, volume, density …… • Area = Length  Length SI unit for area = m2 • Volume = Length  Length  Length SI unit for volume = m3 • Speed = Length / time SI unit for speed = m/s • Density = Mass / Volume SI unit for density = kg/m3 • In 2008 Olympic Game, Usain Bolt sets world record at 9.69 s in Men’s 100 m Final. What is his average speed ?

  26. Other Unit System • U.S. customary system: foot, slug, second • Cgs system: cm, gram, second • We will use SI units in this course, but it is useful to know conversions between systems. • 1 mile = 1609 m = 1.609 km 1 ft = 0.3048 m = 30.48 cm • 1 m = 39.37 in. = 3.281 ft 1 in. = 0.0254 m = 2.54 cm • 1 lb = 0.465 kg 1 oz = 28.35 g 1 slug = 14.59 kg • 1 day = 24 hours = 24 * 60 minutes = 24 * 60 * 60 seconds

  27. Unit Conversion • Example: Is he speeding ? • On the garden state parkway of New Jersey, a car is traveling at a speed of 38.0 m/s. Is the driver exceeding the speed limit? • Put 1’s using unit conversion relations, as many times as necessary. • Multiply or divide numbers and units. • Begin with 38.0 m/s = (38.0 m/s)  1 • Since 1 mile = 1609 m, so we have 1 = 1 mile/1609 m • Then (38.0 m/s) (1 mile/1609 m) = 2.36  10-2 mile/s • 2.36  10-2 mile/s = (2.36  10-2 mile/s)  1  1  1 = (2.36  10-2 mile/s) (60 s/1 min) (60 min/1h) = 85.0 mile/h

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