1 introducation to physics t
- 1. Chapter 1 Introduction to Physics Cikgu Desikan Edited by SMK Changkat Beruas, Perak Cikgu Khairul Anuar SMK Seri Mahkota, Kuantan PHYSICS FORM 4 In collaboration with
- 2. FORM4PHYSICS 2016 1. Understanding Physics 2. Understanding base quantities and derived quantities 3. Understanding scalar and vector Quantities 4. Understanding measurements 5. Analysing scientific investigations Analysis of Past Year Questions Learning Objectives : Dear students, With the new day comes new strength and new thoughts. Introduction to Physics Chapter 1 2007 2008 2009 2010 2011 2012 2013 2014 2015 P1 3 3 3 2 3 3 4 1 P2 A - - - 1 - 1 - - B - - - - - - - - C - - - - - - - - P3 A - 1 1 1 - - 1 - B - - - - - - - -
- 3. Concept Map Dear students, By failing to prepare, you are preparing to fail !!! Introduction to Physics Physics Concepts Physics Quantity Measurement Scientific Investigation Field of Physics Base Quantity Approximation Introduction to Physics Derived Quantity Base Unit Derived Unit Prefix Scientific Notation Conversion of Units Instrument for Measurement Error Accuracy Sensitivity Consistency Chapter 1
- 4. 1.1 Understanding Physics Physics is the study to find a rational explanation (why and how) about the nature of matter, energy and natural phenomena. What is Physics? Fields of study in physics 1.__________ & ________ Investigate the action of force and motion 2. _________________ Studies the influence of heat on different types of matter 3. ________________ Explains the different phenomena due to light 4. _________________ Understand the properties of different types of waves and their uses 6. ___________ Studies the use of electronic devices in various fields 5. _______________ Investigates the interactions of electric & magnetic fields 7. ______________ Study of nuclear structure and their application 4 Heat Forces Motion Nuclear Physics Electronics Electromagnetism Waves Light
- 5. Derived quantities (symbol) Expressed in base quantities Derived units Area, A Area = length x width m2 Volume, V Volume = length x width x height m3 1.2 Physical Quantities Physical Quantities is a physical characteristic that can be measured. All physical quantities can be classified into two groups : 1. ____________________________ 2. ____________________________ Base quantities Base quantities are quantities that cannot be ___________ in terms of other base quantities. Base quantity Symbol S.I. Unit Symbol for S.I. Unit Length L meter m Mass m kilogram kg Time t second s Current I Ampere A Temperature T Kelvin K Derived quantity is one which obtained by __________________ base quantities by multiplication, division or both these operations. Its unit is derived from a similar combination of the base units. 1 2 5 Derived quantities Base quantities Derived quantities derived combining
- 6. 6 Derived quantities (symbol) Expressed in base quantities Derived units Density , ρ kgm–3 Velocity , v ms–1 Acceleration, a ms–2 Momentum, p Momentum = mass x velocity kgms–1 Force, F Force = mass x acceleration N / kgms–2 Pressure, P Nm–2/ Pa / kgm–1s–2 Weight, W Weight = mass x gravitational acceleration N / kgms–2 Volume Mass Density Time ntDisplaceme Velocity Area Force Pressure Time velocityinChange onAccelerati
- 7. Scientific form Write the following quantities in standard form : The values of measurements which is either very large of very small are written in Standard Form so as to be neater, brief and easier to read. A x 10n , 1 < A < 10 and n = integer Prefix Value Standard form Symbol Tera 1,000,000,000, 000 1012 T Giga 1,000,000,000 109 G Mega 1,000,000 106 M Kilo 1,000 103 k Hecto 100 102 h Deca 10 101 da Deci 0.1 10−1 d Centi 0.01 10−2 c Mili 0.001 10−3 m Micro 0.000 001 10−6 μ Nano 0.000 000 001 10−9 n Pico 0.000 000 000 001 10−12 p Prefix is used to simplify the expression of very big or very small numerical values of physical quantities 7 a. Radius of the earth = 6 370 000 m b. Mass of an electron = 0.000 000 000 000 000 911 kg c. Size of a particle = 0.000 03 m d. Diameter of an atom = 0.000 000 072 m e. Wavelength of light = 0.000 000 55 m Prefixes Ans : 6.37x 106 m Ans : 9.11x 10 -16 kg Ans : 3 x 10 -5 m Ans : 7.2 x 10 -8 m Ans : 5.5 x 10 -7 m
- 8. Convert each of the following measurements into metre, m (a) 2.98 Tm (b) 298 km (c) 2.98 μm (d) 2.98 x 10-1 Gm (e) 2.98 x 10-3 Mm (f) 29.8 x 107 nm (g) 298 x 104 μm 8 Conversion of Units Exercise 3.1 (a) 2.98 x 1012 m (b) 2.98 x 103m (c) 2.98 x 10-6m (d) 2.98 x 108m (e) 2.98 x 103m (f) 2.98 x 10 -2 m (g) 2.98 x 10 -2 m
- 9. 9 Convert a. 4 m2 into the units of cm2 b. 30 cm2 into the units of m2 c. 2.5 m2 to unit of mm2 d. 500 mm2 into the units of m2 e. 200 m3 into the units of mm3 f. 11.5 cm3 into the units of m3 g. 72 km h-1 into the units of ms-1 h. 5 g cm-3 into the units of kg m-3 a) 4 x 104 m2 b) 3 x 10-3 m2 c) 2.5 x 106 m2 d) 5 x 10-4 m2 e) 2 x 1011 m2 f) 1.15 x 10-5 m2 g) 20 ms-1 h) 5000 kgm-3
- 10. 1.3 Scalar and Vector Quantities Distance(s) Displacement(s) Total length of the path traveled Distance between two points measured along a specific direction Scalar quantity Vector quantity Speed Velocity Rate of change of distance Rate of change of displacement Speed = Velocity = Scalar quantity Vector quantity 10 Scalar Quantities Vector Quantities Quantities that have magnitude but no direction Quantities that have both magnitude and direction Distance Displacement Speed Velocity work Acceleration Area Force Mass Momentum Examples time distance time ntdisplaceme
- 11. Consistency Accuracy Sensitivity Shooter Consistency Accuracy A High Low B Low High C High High D Low Low The diagram shows the result for four shooters A, B, C and D in a tournament. Every shooter shot five times. (Use High / Low) 11 1.4 Measuring Instruments Consistency in measurements refers to how little deviation there is among the measurements made when a quantity is measured several times. Accuracy of a measurement is how close the measurement made is to the actual value of the quantity. Sensitivity of an instrument is its ability to detect a small change in the quantity to be measured in a short period of time.
- 12. ERROR Error is uncertainty caused by measuring instrument or the observer or the physical factors of the surroundings. Systematic Error Random Error Caused by: i. Condition of the measuring instrument ii. Condition of environment Caused by: i. Surroundings factors, such as temperature and wind ii. Carelessness of the observer Example i. ______________________________ ii. Inaccurate calibration Example i. Parallax error ii. Error in counting iii. Natural errors (sudden change) Way of correction i. Proper calibration ii. Adjust the instrument frequently Ways of correction i. Take several readings and calculate the average value. A parallax error is an error in reading an instrument because the observer’s eyes and pointer are not in line / perpendicular to the plane of the scale. 1. position of eyes must be in line/ perpendicular / 90o with the scale of the reading to be taken. 2. When taking reading from an ammeter, we must make sure that the eyes are exactly in front of the pointer, so that the reflection of the pointer in the mirror is right behind the pointer. In other words, the reflection of the pointer on the mirror could not be seen by the observer, then it is free from parallax error. How to avoid parallax error? 12 Parallax Error zero error
- 13. Measuring Instruments & Accuracy Physical Quantity Measuring Instrument Length Pembaris meter, Angkup vernier , Tolok skru mikrometer Current Ammeter Mass Neraca tiga palang Temperature Termometer Time Jam randik (analog, mekanikal) Voltage Voltmeter 13 Parallax Error A B C 1 2 3 Accurate reading = 2.6 cm Reading = 2.7 cm Reading = 2.6 cm Reading = 2.5 cm B A C Reading = 15.0 ml Reading = 15.1 ml Reading = 14.9 ml 15 16 14 Pointer’s image can be seen Pointer’s image is behind the pointer
- 14. Depth probe Measure depths Outside jaws Measure external diameter of an object Vernier scale (in) Retainer Block movable parts Vernier scale (cm) Main scale (cm) Main scale (in) Inside jaws Measure internal diameter/ thickness of an object VERNIER CALLIPER Measurements Reading from main scale : Reading from main Vernier scale : Reading of Vernier caliper : 14 3.2 cm 0.04 cm 3.24 cm
- 15. 15 10 0 5 10 Negative zero error Main Scale Vernier Scale Positive zero error Sixth mark on the Vernier scale is in line with a mark on the main scale Positive zero error = +0.06 cm 10 0 5 10 Main Scale Vernier Scale Sixth mark on the Vernier scale is in line with a mark on the main scale Negative zero error = - 0.04 cm No zero error Main Scale Vernier Scale cm 0 0 5 10 1
- 16. 16 1. Write down the readings shown by vernier calipers in the following figures: 0 1 0 105 b)0 1 0 105 a) Try this !!! 0 1 0 105 d)0 1 0 105 c) +0.03 cm - 0.06 cm +0.01 cm - 0.03 cm
- 17. Reading of the main scale = 4.00 mm Reading of the thimble scale = 0.44 mm Diameter of ball bearing = 4.44 mm 17 MICROMETER SCREW GAUGE The object which to be measured is placed between the jaws (spindle). The thimble is turned until its jaw touches the object. The ratchet knob prevents overtightening by making a click sound when the micrometer is ready to be read. main scale Vernier scale Horizontal reference line
- 18. 0 0 5 40 45 0 0 5 40 10 45 No Zero Error 18 To elliminate the zero error *** Correct Reading = Reading Obtained − Zero Error Horizontal reference line 0 mark 0 0 5 10 45 Horizontal reference line 2nd mark above 0 Horizontal reference line 3th mark below 0 Positive zero error = Negative zero error =+ 0.02 mm - 0.03 mm Positive zero error Negative zero error
- 19. 0 105 2 3c) 0 105 3 4a) 0 105 1 2d) 0 105 6 7b) Latihan 3.4 2. Write down the readings shown by the following micrometer screw gauges. a) b) 19 4.71 mm 9.17 mm 2.96 cm 2.12 cm 6.66 cm 1.11 cm 0 20 15 25 0 5 15 20 1. Write down the readings shown Vernier calipers in the following figures:
- 20. 20 3. The following diagram shows the scale of a vernier callipers when the jaws are closed. The following diagram shows the scale of the same vernier callipers when there are 50 pieces of cardboard between the jaws. Determine the thickness of one piece of cardboard. 0 1 0 105 5 6 0 105 (a) (b) - 0.04 cm 5.64 cm Zero error : - 0.04 cm Reading of Vernier caliper : 5.64 cm Thickness of 50 cardboards : 5.64 cm – (-0.04 cm) = 5.68 cm Thickness of 1 cardboard : 5.68 cm / 50 = 0.1136 cm
- 21. 20 30 21 Metre Rule A V Ammeter Voltmeter Thermometer Mercury Bulb Mercury column Sensitivity & Accuracy of Measuring Instruments Digital Stopwatch
- 22. Instrument Sensitivity Accuracy Metre Rule 0.1cm 0.1cm Vernier Calliper 0.01 cm 0.01 cm Micrometer Screw Gauge 0.001cm /0.01mm 0.001cm /0.01mm Ammeter (0 – 5 A) 0.1 A 0.1 A Miliammeter (0 – 50 mA) 1 mA 1 mA Thermometer (-10 ºC – 110 ºC) 1 oC 1 oC Mechanical stopwatch 0.2 s 0.2 s Digital stopwatch 0.01s 0.01s 22 Miliammeter Mechanical Stopwatch
- 23. 1.5 Scientific Investigation ______________________________ The quantity whose values we deliberately choose to change or a primary variable which causes other secondary variable to change. ________________________________ The quantity whose value depend on the manipulated variable or a secondary variable which changes in response to the change in the manipulated variable. ________________________________ The quantity whose value is kept constant throughout the experiment. 23 Identifying the problems/ questions / situations Identifying the variables involve Forming a Hypothesis Recording and Presenting data Design and Carry out an experiment Analysing and Interpreting data Making conclusion Writing a Report The problem is identified and stated by asking question. The problem is usually arised from an observation The question asked must be one that can be solved experimentally. 2 1 Identifying the variables involve Manipulated variable Identifying the problems/ questions / situations Responding variable Constant variable
- 24. A general statement about the relationship between a manipulated variable and a responding variable. The hypothesis should be written as : The greater the………, the greater the……. or The bigger the…………, the smaller the….. 3 4 24 Form A Hypothesis Design and Carry out an experiment Aim A statement to show the investigation of the variables involve. The aim of the experiment should be written as: To investigate the relationship between ………..and ……………… Apparatus List the apparatus and materials used so that at least a set of data for manipulated and responding variables can be determined. State the arrangement of the apparatus that can function by drawing a labeling diagram. Procedure 1. State the method of controlling the manipulated variables 2. State the method of measuring the responding variables 3. Repeat the experiments at least four times.
- 25. When the data is organised in a table, it is easier to analyse than recorded randomly. 5 6 7 8 25 Recording and Presenting data Analysing and Interpreting data Making conclusion Writing a Report Plot a graph of ( Responding variable) against (Manipulated variable) How to analyze the data ? (a) Determine the relationship between two variables. (b) Determine the gradient of the graph Based on the analysis and data interpretation, make a rational conclusion Report must be written after the scientific investigation is completed. The report must consist of aim, problem statement, hypothesis, variables, apparatus and material, procedure, result, discussion and conclusion.
- 26. x y 0 y increasing linearly with x x y 0 y decreasing linearly with x F a a ∝ F m a 1 m a 0 0 0 a ∝ 1 m a ∝1 m a is directly proportional to F a is inversely proportional to m a is directly proportional to 1 m Relationship between two variables 26
- 27. 2. Which of the following is the best graph ? The equation of the graph above is A) P = 10Q + 5 B) P = 2Q + 10 C) P = – 2Q + 10 D) P = 5Q – 10 1. Which of the following force-compression graphs shows that the compression,x of a spring is directly proportional with the force that is applied, F? 3. A. B. x F x F x F x F 27 C. D. A. B. x x F F C. D. x x F F Q P 5 10 Revision Questions
- 28. 28 4. Table shows the readings of the length of a rod as recorded by two students, X and Y Reading of student X/cm Reading of student Y/cm 2.42 2.43 2.38 2.41 2.40 2.38 2.36 2.34 a) What was the instrument used by both students? b) Why four readings were taken for each measurement? c) What is the average value of the readings made by i) student X ? ii) student Y ? d) Which set of reading is more accurate? Why? e) Apart from the instrument in (a), what instruments can be used although they are less accurate? cm39.2 4 36.240.238.242.2 cm39.2 4 34.238.241.243.2 a) Vernier caliper b) To increase the accuracy c) (i) student X (ii) student Y ? d) Both are same accurate. Their average readings are the same. e) Meter ruler Answers :
- 29. Load W/N Time for 10 oscillations, t/s Period of oscillation, T/s T2/s2 W/T2 N s-2 1.0 6.7 0.67 0.449 2.228 2.0 9.5 0.95 0.903 2.216 3.0 11.6 1.16 1.346 2.229 4.0 13.4 1.34 1.796 2.228 The above table shows the experimental data that is obtained by a student using the weighted spring oscillation system. a) Name the variable that is manipulated. b) Name the variable that responds. c) Complete the above table with the corresponding values. d) State the derived unit for W/T2. e) Draw the graph of T2 against W. f) Interpret the shape of the graph that you have drawn. g) Calculate the gradient of your graph. h) Write relationship between the load and the period. 5. 29 a) Weight of load, W b) Period of oscillation, T d) kgms-3 / N s-2 f) A straight line originated from 0 and with positive gradient. g) 0.453 N -1s2 h) T2 directly proportional with W Answers :
- 30. W T2 1 2 3 40 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 / s2 / N 1 23 4 5 67 W/N T2/s2 1.0 0.45 2.0 0.90 3.0 1.35 4.0 1.80 453.0 85.05.3 4.06.1 m 30