Physics OCR Chapter 2 (Foundations of Physics) 5.0 / 5 based on 1 rating ? PhysicsFoundations of PhysicsA2/A-levelOCR Created by: CharliegageCreated on: 11-04-17 12:07 Quantities and Units Quantity - Is a property of an object or a phenomenon that can be measured Scientists use a standard system of units abbreviated to SI SI Base Units SI is built around seven base units, which are the standard set of units 1 of 4 Prefixes Prefixes SI uses prefixes to show multiples of factors of the units. e.g. km = Kilometer (The prefix is 'Kilo' the SI base unit is 'meter') 2 of 4 Scalar and Vector Quantities Scalar Quantities - Has a magnitude but no direction Scalar quantities can be added and subtracted together in the usual way Scalar quantities must have the same units when added or subtracted Scalar quantities can also be divided or multiplied together and the units can be the same or different, final units have to be worked out Vector Quantities - Has magnitude and direction Vectors in parallel and antiparallel are added Perpendicular Vectors: Perpendicular vectors act at right angles to one another You can use Pythagoras theorem to find magnitude of the resultant vector You can use trigonometry to find the angle 3 of 4 Resolving Vectors Resolving Vectors into Two Components Can be done using a scale diagram Easier to use equation A force can be split into two parts the x and y directions The equations are: F x = F Cos X F y = F Cos X 4 of 4

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