1. Chapter-1 Measurements

2.  Discovery of Physics: Through measuring Physical Quantities such as length, time, mass, temperature, pressure and electric current  Units and Standards. Measurements of Physical quantity in its own Unit by comparison with a Standard.  Each physical quantity has its own unit and each unit has its own standard  Two groups of Quantities: Base and Derived  Base Physical Quantities : Length (L), Mass (M) and Time (T)  Derived Physical Quantities: (Ratio or Product of two Base Units) speed = length/time acceleration = speed/time force = mass x acceleration Ch 1-2 Measuring Things

3.  Two Groups of Units:  Base Units: Length, Time, Mass  Derived Units: length/time; mass x velocity  Base-Standards associated with base Units  Derived-Standard associated with derived Units  Base Unit System International System (mks) Gaussian System (cgs) British engineering system (fps)

4. Table of Base Units SystemLengthMassTime SI(mks)meter (m)kilogram (kg) second (s) Gaussian (cgs)centimeter (cm) gram (g)second (s) British (fps)foot (ft)slug *pound second (s)

5. Prefix for SI units FactorPrefixSymbolExample 10 12 teraTT Bytes 10 9 gigaGG Bytes 10 6 megaMM Volt 10 3 kilokkg 10 -2 centiccm 10 -3 millimmm 10 -6 micro  gg 10 -9 nanonns 10 -12 picopps Prefix: Prefix are used to increase or decrease SI units

6. Ch 1-4 Changing Units-Chain-link conversion  Changing units using Chain-link conversion Multiplication of original measurement by a conversion factor c [ ratio of units ( new unit/old unit)]  Change of 5 min into seconds conversion: 1 min=60 s or 1 min/60 s = 1 60 s = 1min or 60 s/ 1min= 1 Conversion factor c = 60 s/1 min 5 min= 5 min x c = 5 min x (60 s/1 min)=300 s  Conversion factor f for changing year into seconds f =(365 days/1year)x(24 h/1day) x (60 min/ 1 h) x (60 s/1 min)

7. Significant Figures  Precession in data given by Significant Figures Significant Figures (SF): number of digits in a number, 33 m/s has two digits hence two SF 1.33 m has three SF  Final Result of a calculation cannot be more precise than the least significant figure in the data  Z = A(2 SF) x B(3 SF) Z will be rounded off to have 2SF number  3.15 or 3.15 x10 3 has 3SF  3000 has 4SF or 3 x10 3 has 1SF or 3.0 x10 3 has 2SF or 3.00 x10 3 has 3SF or 3.000 x10 3 has 4SF or

8. Ch 1-5 Standard of Length  SI Standard of length-meter Length of a platinum-iridium bar (standard meter bar) kept at International Bureau of Weights and Measures near Paris  SI Standard of length using speed of light c= 299792458 m/s The meter is the length of the path traveled by light in a vacuum during a time interval of 1/299792458 of a second:

9. Ch 1-6 SI Standard of Time  SI Standard of time-second Any phenomenon that repeats itself is a possible time standard  Time measurement with reference to frequency (f=9,192,631,770 Hz) of light emitted by cesium-133 atom (atomic clock)  One second is the time taken by 9,192, 631,770 oscillations of light emitted by a cesium-133 atom

10. Ch 1-7 SI Standard of Mass  SI Standard of mass-kilogram Mass of a platinum-iridium cylinder ( The Standard kilogram) kept at International Bureau of Weights and Measures near Paris.  Second Mass Standard Atomic mass unit (amu): 1 amu= 1.6605402 x 10 -27 kg

11. Dimensional Analysis  Dimension denotes qualitative nature of a physical quantity  Symbols L, M, T are used to specify length, mass and time nature of a physical quantity respectively.  The brackets [ ] are used to denote the dimension of a physical quantity velocity v and area A  [v] = L / T ; [A] = L 2  Dimensions are treated as algebraic quantities and can be multiplied or divided mutually

12. Dimensional Analysis  Dimensional Analysis is used to check a formula  A formula is correct only if the dimension of both side of the relationship are same.  Example: Acceleration of a particle moving in a circle is given by : a=kr n v m Determine the values of constant k and exponents n and m  The dimensional equation is L/T 2 =L n (L/T) m =L n+m /T m Equating exponents of L and T separately: 1=n+m; 2=m; m=2; n=1-m=1-2=-1 Then L/T 2 = k L/T 2 ; and k=1 Hence a=kr n v m = r -1 v 2 = v 2 /r