Principles of Physics

 motion along a straight line path, motion in one dimension  Which way are you headed?  How far did you go?  How fast are you going?  Is your speed changing?

Direction  In order to get anywhere you need to know what direction you are headed.  North, South, West, East  Up, Down, Left, Right  Direction can also be negative or positive for math purposes  Negative: South, West, Down, Left  Positive: North, East, Up, Right

Almost all quantities have units - examples: meters, seconds, kilograms - Without units numbers would be meaningless Vector – Quantities that include a direction  Vectors can be drawn  They are represented by arrows Example: 12 m south Scalar – Quantities that do not include direction Example: 4 seconds

Path length (p): total length of path taken - measured in meters(m) - scalar quantity (does not include direction) How far did you go? 8 m 6 m 2 m 1 m p = 8 m + 6 m + 2 m + 1 m p = 17 m

Displacement (d): change in position, shortest path between start and finish - vector (amount and direction) - How far did you go? 8 m 6 m 2 m 1 m

6 m3 m Path Length = Displacement =9 m9 m right 6 m 3 m Path Length = Displacement =9 m3 m left 6 m 3 m Path Length = Displacement =9 m?

 To determine displacement draw a diagram of the path taken  Example: 8 m east, then 6m north, then 2 m east, then 1 m south  Simplify the diagram to a right triangle  Use Pythagorean Theorem to determine the displacement 8 m 6 m 2 m 1 m 8 m 6 m 2 m 1 m 10 m 5 m

Jan walks 4 meters north then turns to walk 4 meters east and finally turns to walk another 8 meters north. Determine Jan’s displacement. 4 m 8m 4 m 8m d

Units for path length or displacement: Standard Unit: meter Anything else must be converted  1 meter = 100 centimeters =.001 kilometer  1 kilometer = 1000 meters  1 meter = 3.28 feet  1 kilometer = miles

Smaller unit to larger unit: divide  centimeters to meters: divide by 100  millimeters to meters: divide by 1000 Larger unit to smaller unit: multiply  kilometers to meters: multiply by 1000

Smaller unit to larger unit: divide 1. Change 40 centimeters to meters Larger unit to smaller unit: multiply 2. Change 6.8 kilometers to meters