2 Scientific models Used to solve complex questions 3 types Physical model-Something you can physically manipulateThe car and ramp are examplesConceptual model-Descriptive models usually describing how something worksCopernicus describing how planets revolve around sunGraphical modelShows relationship between 2 variables
3 Graphical modelsCan use graphs to predict values that you did not measureEx. Predicting speed in lab 2.1
5 Position vs. distancePosition: where something is compared to where it started including direction- as things move, position changesDistance: interval of length without regard to direction- you could walk in a circle and your position would be the same, but you would have traveled a distanceEx: You walk 7km north away from school, then walk back to the school- What is your position? What is your distance traveled?
6 Position vs. Time Graph The slope of this graph is speed at any given time and position
7 Finding slope in general Choose two points on a graphPt 1 (0.5, 30) Pt 2 (1.5, 60)Use the following formula:The units show you that the slope you found is speed
8 Average vs. Instantaneous speed Average speed- speed that results from whole journeyTotal distance/timeInstantaneous speed- speed at a particular point on the journeyPosition/ time
9 Acceleration Rate of change in speed of an object Formula: Change in speed/change in timeUnits: cm/ sec2
10 Acceleration Occurs when Deceleration- decrease in speed over time You speed upYou slow downYou change directionDeceleration- decrease in speed over time0 acceleration- traveling at a constant rate or stopped