1. PHY HL: Unit 01 Physics and Physical Measurement BY HEI MAN KWOK 12N03S 8.24.2013

2. THE REALM OF PHYSICS – MAGNITUDES

4. Order of Magnitude = power of ten (or power of a base) So 28 and 82 are of the same order of magnitude – both of 10^2 in the hundreds Ratio = difference of orders of magnitude http://quizlet.com/24993011/intro-to-ib- physics-flash-cards/ http://quizlet.com/24993011/intro-to-ib- physics-flash-cards/ Use when appropriate

5. SI SYSTEM OF FUNDAMENTAL AND DERIVED UNITS

6. SI System Fundamental Quantities Mass – kilogram (kg) Length - meter (m) Time – second (a) Electric current – Ampere (A) Amount of substance – Mole (mol) Thermodynamic temperature – Kevin (K) Luminous Intensity – Candela (ca) – DON’T NEED TO KNOW

7. Derived Units All units can be derived (built from) the Fundamental Units eg. Speed/ velocity m s⁻¹ Use scientific notation! 123 => 1.23 x 10^2 m/s => m s⁻¹

9. Unit Conversions (given)

10. MEASUREMENT

11. Measurement Errors Random Errors – due to unknown or unpredictable changes in environmental conditions or measuring instruments eg. Measuring the bounce of the ball – affected by wind Systematic Errors – due to 1) design of the experiment, 2) the measurement device, 3) wrong usage of the instrument eg. ‘zero error’ – ruler with a broken end

12. Measurement Errors Precision – the degree of which taking repeats will produce the same value (reproducibility) Accuracy – the degree of closeness to the real value (accuracy) Reducing Random Error – take more repeats Reducing Systematic Error – find out what is wrong with the method or calibrate instruments and correct it

13. Calculating Uncertainty Calculate values only to the number of sfs at the least precise value used in the calculation Be only as precise as the uncertainty is, ie if its ±500, round answer to the nearest hundred

14. Determining Uncertainty

15. Uncertainties in Graphs Random uncertainty -> uncertainty range (±) - > graphically represented as an error bar Uncertainty in the gradient (x/ y -> sum of percentage uncertainties) Uncertainty in intercepts (same) NOTE: Uncertainties only need to be considered when its significant

16. Graphs can easily show… Outlier – a point that doesn’t fit in the trend – spots mistakes in the data Non-zero intercept – shows systematic error Non-linear relationship Q: Why v is not directly proportional to λ You cannot draw a straight line (linear) through the origin

17. VECTORS AND SCALARS

18. Scalar v Vector Scalar – has a sizeVector – has a size and a direction SpeedVelocity Distance (length)Displacement MassWeight (towards the earth ) VolumeMagnetic Field Strength DensityElectric Field Strength PressureAcceleration GPEMomentum KEDrag VoltageForce Current Resistance

19. Sum or difference of two vectors

20. Vectors in one dimension When considering simple examples where motion is restricted to 1d Right + Left – ; North + South – ; Up + Down – Taking components of a vector

21. 1.3.3 Resolve vectors into perpendicular components along chosen axes. http://ibguides.com/physics/notes/vectors- and-scalars http://ibguides.com/physics/notes/vectors- and-scalars