Group Activity Measurement Measure assigned objects with the use of the following devices: 1 foot/talampakan (length of a foot) 2 cubit (distance from elbow to tip of middle finger) 3 timuro (length of a forefinger) 4 palm (width of four fingers excluding thumb) 5 digit/dali (thickness of thumb) 6 uncia (width of thumb) 7 yard (distance from nose to the tip of middle finger 8 dipa (distance from tip middle finger to tip of other middle finger) 9 Kings foot (assign a king in your group) Measurement and Quantities Physical Quantity a quantity that can be measured consists of a numerical magnitude and a unit Physical Quantity Fundamental Quantity DerivedQuantity also called base quantity is a quantity that cannot be expressed in terms of other physical quantities International System (SI) of Units if a physical quantity is not in SI unit, it can be CONVERTed into SI unit. Fundamental Quantity SI Unit Length, lmeter, m Mass, mkilogram, kg Time, tsecond, s Temperature, Tkelvin, K Current, Iampere, A Amount of substance, nmole, mol Luminous Intensity, Icandela, cd 30 min = ? s Derived Quantities are obtained from a combination of various fundamental quantities their units are determined from the relation between the fundamental quantities and the derived quantities Derived Quantity SI UnitRelationship Aream2m2 length x width Volumem3m3 length x width x height Densitykg/m 3 mass/volume Velocitym/sdisplacement/time Accelerationm/s 2 velocity/time Force kg m/s or N mass x acceleration Pressure kg/m.s 2 or Pa force/area 50km/h = ? m/s Prefix Multiplying Factor Symbol nano n micro milli m centi c deci d kilo-10 3 k mega-10 6 M giga-10 9 G Physical Quantity Scalar Vector Scalar Quantity is a quantity which can be fully described by its magnitude Examples: speed, mass, time, length, density, energy and work. Total work done by the girl in the picture is 50 J. The direction is not important to describe a scalar quantity. Vector Quantity is a quantity which can only be described fully by its magnitude and direction Examples: velocity, weight, displacement, acceleration and momentum Common Errors in Writing Units of Quantities POINT at the end of the unit min.m.kg. ---WRONG! Plural form of a unit mins.kgs.lbs.cms. amps. ---WRONG! Wrong abbreviation sec.mtr. ---WRONG! Significant Concepts Scientific Notation Significant Figures Conversion of Units 1 kg = 2.2 lb 1 in = 2.54 cm 1 yd = 3 ft 1 ft = 12 in 1 hr = 60 min 1 min = 60 s 1 d = 24 hr 1 mi = km 1 byte = 8 bits Convert the following quantities: 1) kg = ____ lb 2) 1.0 GB = ____ bits 3) 2.50 km = ____ mi 4) 6 ft 1/2 in = ___ cm 5) 1 common year = ___ s 6) 220 lb = __ kg 7) 100,000 s = ___ d 8) 25 mi = ___ m