ISCI3001 Principle of Physics Navapadol Kittiamornkul, Ph. D.

Transcription

1 ISCI3001 Principle of Physics

2 Chapter 1: Physics and Physic Quantity Chapter 1: Physics and Physic Quantity

3 Chapter 1: Physics and Physic Quantity 1.1 The Application of Physics 1.2 Models, Theories and Laws 1.3 Experiments 1.4 Basic Unit: Length, Mass and Time 1.5 Derived Units 1.6 Unit analysis 1.7 Unit Conversion 1.8 Type of Physic Quantities 1.9 Properties of Vector

4 Introduction Physics is branch of science that study natural phenomena.

5 What is the importance of physics Example of Physics in Nursing Science 1. Body temperature can reduce rapidly using alcohol. 2. Physical Therapy in water. 3. Principle of Ultrasound. 4. Pressure measurement 5. ETC.

6 1.1 The Application of Physics Sport and Exercise Body Temperature

7 1.1 The Application of Physics Hearing Blood Flow and Blood Pressure

8 1.1 The Application of Physics Traction System Physical Therapy

9 1.1 The Application of Physics Ultrasound Microwave heating Therapy

10 1.1 The Application of Physics X-ray Medical Spectrum Analysis

11 1.1 The Application of Physics Benefit of Physic study 1. Reason 2. Brain Training 3. History 4. Future

12 1.2 Model, Theory, Law Model Model can show something that we cannot directly see, hear or touch. Example: Bohr s atomic model looks like planet orbit.

13 1.2 Model, Theory, Law Theory Theory compensates model when it is accepted and uses widely. Example: Wave theory of light.

14 1.2 Model, Theory, Law Law Law shows nature phenomena used model and theory to describe it. Example: Law of Gravity that Gravitation force (F g ) depends on masses (M 1, M 2 ) and displacement.

15 1.3 Experiment Experiment Model, Theory and law are used to experiment. On the other hand, Experiment can prove model, theory and law Experiment PROVE Model, Theory and Law Example: Plasma ball experiment in laboratory.

16 STRUCTURE PHYSICS STRUCTURE PHYSICS Classical Physics - Low speed material - Huge material Modern Physics (Quantum Physics) - High speed material (closely to light speed) - Very small material (atom, particle, etc.)

17 1.4 Basic Unit: Length, Mass and Time Length Length in S.I. Unit System uses meter (m). Previously, 1 m = 1/10,000,000 of distance from equator to north pole.

18 1.4 Basic Unit: Length, Mass and Time Mass Mass is amount of matter that uses kilogram (kg) in S.I. Unit System. - Based on International Prototype kilogram, a cylinder of platinum-iridium alloy kept near Paris - Mass of this cylinder depends on amount of atom that is always constant

19 1.4 Basic Unit: Length, Mass and Time Time Time in S.I. Unit System uses second (s). - Previously, 1 second = 1/86,400 of time in 1 day, but 1 day time can change depending on change of earth mass and tide. - Therefore, we use the vibration of Cesium atom that vibrates 9,192,631,770 times.

20 1.4 Basic Unit: Length, Mass and Time In present, The definition of 1 second is changed to 1/light speed that travels in 1 second.

21 1.5 Derived Units Derived Unit is created by Basic unit. Example: Speed can be derived by distance divided by time Therefore, Unit of speed is meter/second or m/s

22 1.5 Derived Units Amount S.I. Units Symbol Force Newton N, kg m/s 2 Velocity Meter/second m/s Acceleration Meter/second 2 m/s 2 Area Square meter m 2 Flow rate Cubic meter/second m 3 /s Pressure Pascal Pa, N/m 2 Density Kilogram/cubic meter Kg/m 3 Specific Weight Newton/cubic meter N/m 3 Dynamic viscosity Pascal second Pa s Power Watt W

23 1.6 Unit analysis Unit analysis is very important in Physics because in every equation, the unit of quantity on the left of equation must be the same as unit of quantity on the right of equation V 2 = U 2 +2as (m/s) 2 = (m/s) 2 + (m/s 2 )(m) (m/s) 2 = (m/s) 2 + (m/s) 2 (m/s) 2 = 2(m/s) 2

24 1.6 Unit analysis Ex 1.1 Prove the following equation that it has correct unit

25 1.7 Unit Conversion

26 1.7 Unit Conversion Metric Unit Imperial Unit Length meter foot Weight kilogram pound Distant kilometer mile Temperature C F We have many units in the world. So, We need to study how to convert these units.

27 1.7 Unit Conversion

28 1.7 Unit Conversion Ex. How to convert 1 year to seconds? Ex. How to convert 10 mile/hr to km/hr? (Hint: 1 mile = 1.6 km) (Answer: 16 km/hr)

29 1.7 Unit Conversion Ex. Car gauge shows its speed in km/hr. If this car move with 72 km/hr, calculate this speed into m/s (Answer: 20 m/s)

30 1.7 Unit Conversion Moreover, We can convert unit using prefix. prefix prefix

31 1.7 Unit Conversion The prefix table

32 1.7 Unit Conversion Ex. Convert 1 cm to nm From We got

33 1.7 Unit Conversion Ex. Generator can generate electric power 1 kw. If we have 50 w light bulbs, how many bulbs that this generator can give its power? (Answer: 20 lamps)

34 1.8 Type of Physic Quantities Physic Quantities Scalar A quantity represented by a mathematical scalar, or one that is usually said to be described by a single real number. Ex. Time, height, mass, money, etc. Vector In physics and geometry, it used to represent physical quantities that have both magnitude and direction. Ex. Force, velocity, acceleration, weight, etc.

35 1.8 Type of Physic Quantities We have to indicate both magnitude and direction, when we indicate about vector quantity. Saying vector quantity The man is driving a car with velocity of 100 km/hr to the north. magnitude direction Figure of vector quantity Vector can be showed by straight line with arrow magnitude direction

36 1.8 Type of Physic Quantities Writing vector quantity We can use Bold English character. Example: vector A A vector B B We can use English character with arrow. Example: vector A A vector B B We can indicate only magnitude of vector using absolute sign. Example: magnitude of vector A ǀAǀ magnitude of vector B ǀBǀ

37 1.9 Properties of Vector Definition 1: Equality of vectors Two vectors are equal if they have the same magnitude and the same direction. Equality of vectors

38 1.9 Properties of Vector Definition 2: Negative vector A negative vector is a vector that has the opposite direction to the reference positive direction. Negative vectors

39 1.9 Properties of Vector Addition of Vectors We have 2 methods to add two vectors together. Method 1: Connecting Head-to-Tail Connect tail of 1 st vector to head of another vector.

40 1.9 Properties of Vector Method 2: Draw Parallelogram Connect tails of two vectors and draw parallelogram.

41 1.9 Properties of Vector Ex. Find the adding resultant vector from giving vectors shown as follows.

42 1.9 Properties of Vector Commutative Law of Addition A + B = B + A

43 1.9 Properties of Vector Associative Law of Addition (A + B)+ C = A + (B + C)

44 1.9 Properties of Vector Subtraction of vectors Use definition of negative vector. Then, do adding vector. -B A A A-B A B -B A B = A + (-B)

45 1.9 Properties of Vector Multiplication of vectors When multiply vector with scalar, we will get the same direction vector with higher or lower magnitude depending on multiplier.

46 1.9 Properties of Vector Component of vectors In a two-dimensional coordinate system, any vector can be broken into x-component and y-component. According to Figure, the components of vector A can be indicated by A x and A y. We can use following equation to describe the component of vector A A = A x + A y

47 1.9 Properties of Vector Unit Vectors Vector that has its magnitude equal to 1 unit called unit vector. Each axis in coordinate system has its unit vector. Unit vector in x-axis i Unit vector in y-axis j A = A x i + A y j

48 1.9 Properties of Vector Unit Vectors

49 1.9 Properties of Vector Ex. Give A = 2i + 6j, B = 5i + 3j, C = 4i + 2j 1.) A + B + C (Answer: 11i + 11j) 2.) A B C (Answer: -7i + 1j) 3.) 2A B 3C (Answer: 11i + 15j)

50 1.9 Properties of Vector How to Break Vector Horizontal Component Vertical Component How to find Magnitude and Direction of Vector A Magnitude Direction

51 Y-axis 1.9 Properties of Vector Ex. Vector G has 10 units of length angled 30 to X-axis. Find component of vector G. G 30 X-axis

52 1.9 Properties of Vector Ex. Components of force in X-axis and Y-axis equal to 50 N and 25 N respectively. Find the magnitude of this force and its direction comparing with X-axis. (Answer: 55.9 N, 26.6 )

53 NURSING MEASUREMENTS Thermal measurements Thermometer Volume measurements Syringe Weight measurements Balance Height measurement Altimeter Time measurements Timers Blood Pressure measurements Sphygmomanometer Heart Rate measurements Stethoscope ETC.

54 END OF CHAPTER 1 END OF CHAPTER 1 Physics and Physic Quantity