This document discusses physical quantities and units in physics. It defines a physical quantity as something that can be measured, like length, weight, or time, and notes that every physical quantity has a magnitude and unit. It discusses unit conversion for areas and volumes using prefixes like milli (10-3). Base units include meters, kilograms, and seconds. Derived units are combinations of base units and must be multiplied or divided, not added or subtracted. Scalar quantities have only magnitude, while vector quantities have both magnitude and direction, and can be represented by arrows. Methods for adding and resolving vectors are also outlined.

1. Physical Quantities and Units As/A Level Physics @ferrytanoto

2. Physical Quantity Is a feature of something which can be measured, e.g. length, weight, or time of fall. Every physical quantity has a numerical value (magnitude) and a unit, e.g. 25 m is the physical quantity of length; 25 is the magnitude and metre is the unit.

3. Prefix

4. Unit Conversion for Areas and Volumes Length 1 mm = 10-3m Areas Squaring both sides 1 mm2 = (10-3)2 m2 = 10-6 m2 Volume Cubing both sides 1 mm3 = (10-3)3 m3 = 10-9 m3

5. Base Units

6. Derived Units consists of some combination of the base units. The base units may be multiplied together or divided by one another, but never added or subtracted

7. Derived Units

8. In any equation where each term has the same base units, the equation is said to be homogeneous or ‘balanced’.

9. A quantity which can be described fully by giving its magnitudeis known as a scalar quantity. A vector quantity has magnitudeand direction.

10. Scalar and Vector Quantities

11. Vector Representation One way to represent a vector is by means of an arrow. The directionof the arrow is the directionof the vector quantity. The lengthof the arrow, drawn to scale, represents its magnitude.

12. Addition of Vectors The combined effect of two (or more) vectors is called the resultant. Coplanar (all in the same plane) vectors may be added (or subtracted) using a vector diagram. The resultant may be found using a scale drawing of the vector diagram of by calculation.

13. Resolution of Vectors A single vector may be divided into two separate components. The dividing of a vector into components is known as the resolution of the vector. In general, a vector is resolved into two components at right-angles to each other.

14. Sine rule

15. Cosine rule

16. Pythagoras’ Theorem Hypotenuse2 = Opposite2 + Adjacent2