Quick !

1. Quick ! What do you think the word MOTION means? Can you define the word motion without using the word MOVE?

2. Consider the following: • How do you know the object moved? • What evidence do you have the object moved? • How would you describe the object’s movement to someone who wasn’t here to see it?

3. How can you tell if an object is in motion? •  By comparing the position of an object against an object that is staying in place. • The object that appears to stay in place is a reference point. • When an object changes position over time relative to a reference point, the object is in motion. • Displacement is defined as change in position, or final position - initial position. • Direction is important

4. Distance/Displacement • To test your understanding of this distinction, consider the motion depicted in the diagram below. A physics teacher walks 4 meters East, 2 meters South, 4 meters West, and finally 2 meters North. (X1+X2+…=D or Xf-Xi=D) • Even though the physics teacher has walked a total distance of 12 meters, her displacement is 0 meters

5. Definition of Motion: Change in position Definition of Reference Point: The point on an object used to determine its position and change of position.

6. What types of measurements could we make to understand motion? • Distance • 2) Time interval

7. Distance Definition of Distance (d): The amount of change in position Formula to calculate distance (d) when initial and final positions are know d = xf - xi

8. Time Interval Definition of Time Interval -- How long it takes for something to happen Formula to calculate a time interval Δt = tf – ti

9. Important Scientific Abbreviaitons: Delta (Δ ): (The Greek letter that means) change Subscript i: Starting or initial Subscript f: Final or ending position

10. Distance and Time Example Karen walks 2 km from her house to the store . If she leaves the house at 1:00 PM and she arrive at the store at 1:30 PM, how far did she travel and how long, in minutes, did it take for her to arrive at the store. How Far = distance traveled How Long = time interval

11. Distance and Time Example How Far = distance traveled Find Distance d = xf - xi xi = 0 km d = 2 km - 0 km = 2 km xf = 2 km How Long = time interval Find Time Δt = tf – ti ti = 1:00 pm Δt = 1:30 PM - 1:00 PM = 30 min. tf = 1:30 pm

12. What is SPEED? Definition of Speed(v)-- the distance traveled by an object divided by the time taken to travel that distance The units of speed are distance per unit of time Examples: Miles per hour……………..mi/hr Kilometers per hour………km/hr Meters per sec……………..m/s

13. Average Speed Formula v = d/Δt

14. Speed Example Jack walks 240 meters up the hill to fetch a pail of water. Jack falls down and tumbles down the hill in 80 seconds. What is the speed of Jack falling down the hill?

15. Speed Example Jack walks 240 meters up the hill to fetch a pail of water. Jack falls down and tumbles down the hill in 80 seconds. What is the speed of Jack falling down the hill? Find

16. Speed Example Jack walks 240 meters up the hill to fetch a pail of water. Jack falls down and tumbles down the hill in 80 seconds. What is the speed of Jack falling down the hill? Find Speed v = d/Δt d = 240 m v = 240 m Δt = 80 s 80 s v = 3 m/s