Physical Quantities and Units http://thinkzone.wlonk.com/Units/PhysQuantities.htm
by Ben Ng
1. Mass
1.1. SI Unit- Kilogram (KG)
1.2. measured via Electronic Beam Balance/ Sliding Balance
1.3. Mass and Weight are NOT the Same!
2. Length
2.1. Metre- length of the path travelled by light in a vacuum during a time interval of 1/299792458 of a second.
2.2. Metre Rule
2.2.1. Accurate to 0.001 m ( 1 millimeter)
2.2.1.1. Max-1.000m
2.2.1.2. Min-0.001m
2.3. Venier Calipers
2.3.1. Accurate to +/- 0.01cm
2.3.1.1. Inside jaws to measure interiors diameters
2.3.1.2. Outside jaws to measure exterior diameters
2.3.1.3. Tail to measure depths
2.4. Micrometer Screw Gauge
2.4.1. Accurate to +/- 0.001 cm
3. Prefixes in units
3.1. To express numbers involving decimals
3.2. 1012 tera T 109 giga G 106 mega M 103 kilo k 102 hecto h 101 deka da Factor Name Symbol 10-1 deci d 10-2 centi c 10-3 milli m 10-6 micro µ 10-9 nano n 10-12 pico p 10-15 femto f
4. Physical Quantity /Base Unit/ Symbol Length / metre / m Mass / kilogram / kg Time / second / s Electric Current / ampere / A Temperature / kelvin / K Luminous intensity/ candela/ Cd Amt of Substance / mole/ mol
5. Time
5.1. Second- Defined as: 9.192.631,700 times the period of oscillation of radiation from the cesium atom
5.2. Digital Stopwatch used to measure short time intervals
5.2.1. Accurate to +/- 0.01 s
5.3. Analogue Stopwatch
5.3.1. Accurate to +/- 0.1 s
5.4. Human reaction error when using stopwatch 0.3 s incurred
5.5. Mechanical instruments: watches/ticker-tape timers
5.5.1. Use repetitive motion/vibrations
5.5.1.1. Known as- Oscillations
5.5.1.2. Time to complete 1 Oscillation= Period of oscillation