1. Describing Motion Chapter 2: section 1 Tuesday 9/26/13

2. 2 Goals for this lesson 1. Describe motion 2. Perform calculations to determine speed 3. Motion and Position A reference point is needed to determine the position of an object Motion occurs when an object changes its position relative to a reference point Ex: How do people in a car know they are moving? Ex: Throw a ball, how do you know it moved 4. Distance vs Displacement Distance - how far an object has moved meter (m) Ex: It takes 4 laps around a 400m track to make approximately a 1 mile race. What is the total distance in meters? Displacement the distance and direction of an object relative to the starting point Ex: a person walks 20 m North, turns walks 10 m West, and then 20 m South, What is the displacement? 5. Speed Speed = s Distance = d Time = t Most common unit = meters per second (m/s) speed=Total distance traveled total time Distance SpeedTime This picture will help with solving problems mathematically without knowing Algebra!! 6. Practice problems 1. A passenger elevator travels from the first floor to the 60th floor, a distance of 210 m, in 35 sec. What is the elevators speed? 2. How far does a car travel in 0.75 hours if it is moving at a constant speed of 88 km/hour? 3. A motorcycle is moving at a constant speed of 40 km/h. How long does it take to travel 10 km? 7. Homework Speed worksheet Tomorrow Motion detector lab 8. Monday 9/30/13 Pick up 9.30 Reinforcement section 1 9. Goals for the lesson 1. Define speed terms 2. Interpret a position time graph 3. Perform calculations to determine velocity 10. Opener for Monday 9/30/13 1. Describe how the skiers velocity changes during the race. 2. Why does the skiers velocity increase as he races downhill? 3. How does being in a tuck position affect a skiers motion? 11. Speed Terms Constant speed if you maintain the same speed over a time interval Changing speed speed up or slow down over a time interval Average speed - describes the speed of motion when speed is changing Instantaneous speed the speed at a given point in time 12. Graphing Motion Time is plotted on the x axis Distance traveled is plotted on the y axis Slope of a distance-time graph = velocity (speed) Steeper line = faster Horizontal line = not moving, no speed Connect the dots with a straight best fit line not a dot-to-dot line Easier to extrapolate data in between points 13. Position (m)Interpreting a graph When is the object stopped? How do you know? When is it moving the fastest? slowest? Explain 14. Velocity Velocity symbol = v Displacement = x Time = t Includes the speed of an object but also the direction of its motion. displacement total time = velocity Displacement Velocity Time 15. Homework Reinforcement sec 1 Quiz Wednesday speed and velocity calculations interpreting graphs describing motion