2. All matter in the universe is constantly in motion, from the revolution of Earth around the Sun to electrons moving around the nucleus of an atom. Matter and Motion 1 1 What is Motion?

3. Something is in motion if it is changing position. Changing Position What is Motion? It could be a fast-moving airplane, a leaf swirling in the wind, or water tricking from a hose. When an object moves from one location to another, it is changing position. 1 1

4. The runners sprint from the start line to the finish line. Changing Position What is Motion? Their positions change, so they are in motion. 1 1

5. An object changes position if it moves relative to a reference point. Relative Motion What is Motion? Picture yourself competing in a 100-m dash. You begin just behind the start line. When you pass the finish line, you are 100 m from start line. 1 1

6. If the start line is your reference point, then your position has changed by 100 m relative to the start line, and motion has occurred. Relative Motion What is Motion? 1 1

7. Displacement includes the distance between the starting and ending points and the direction in which you travel. Distance and Displacement What is Motion? This figure shows the difference between distance and displacement. 1 1

8. Speed is the distance traveled divided by the time taken to travel the distance. Speed What is Motion? Speed can be calculated from this equation: 1 1

9. In SI units, distance is measured in m and time is measured in s. Speed What is Motion? As a result, the SI unit of speed is the m/s—the SI distance unit divided by the SI time unit. 1 1

10. Average speed is found by dividing the total distance traveled by the time taken. Average Speed What is Motion? An object in motion can change speeds many times as it speeds up or slows down. 1 1

11. The speed of an object at one instant of time is the object's instantaneous speed. Average Speed What is Motion? If it takes you 0.5 h to walk 2 km to the library, your average speed would be as follows: 1 1

12. Average speed, instantaneous speed, and constant speed are illustrated here. Average Speed What is Motion? 1 1

13. You can represent the motion of an object with a distance-time graph. Graphing Motion What is Motion? For this type of graph, time is plotted on the horizontal axis, and distance is plotted on the vertical axis. 1 1 Click box to view movie.

14. Look at the graph. Distance-Time Graphs and Speed What is Motion? 1 1 According to the graph, after 1 s student A traveled 1 m. Student B, however, traveled only 0.5 m in the first second.

15. So student A traveled faster than student B. Distance-Time Graphs and Speed What is Motion? 1 1 The line representing the motion of student A is steeper than the line for student B.

16. A steeper line on the distance-time graph represents a greater speed. Distance-Time Graphs and Speed What is Motion? 1 1 A horizontal line on the distance-time graph means that no change in position occurs.

17. What is Motion? Distance-Time Graphs and Speed Both students also traveled the same speed throughout the whole race. They didn’t speed up or slow down! This is called? Constant Speed How can you tell? Because the line is going straight up. It is not curved.

18. If you are hiking in the woods, you want to know not only your speed, but also the direction in which you are moving. Velocity What is Motion? 1 1

19. The velocity of an object is the speed of the object and direction of its motion. Velocity What is Motion? 1 1 This is why a compass and a map are useful to hikers.

20. Velocity has the same units as speed, but it also includes the direction of motion. Velocity What is Motion? 1 1 The velocity of an object can change if the object's speed changes, its direction of motion changes, or they both change.

21. Calculating Time and Distance You can also calculate the time it took an object (you) to travel or the how far you traveled or the distance Time = Distance/Speed Time can be in hours, minutes or seconds Distance = Speed x Time Distance can be in meters, miles or kilometers

22. Section Check 1 1 Question 1 To determine whether something has changed position, you need a _______. A. compass B. global positioning system C. map D. reference point

23. Section Check 1 1 Answer The answer is D. If someone starts a car and drives it 100 meters from its parking spot, the parking spot can be used as a point of reference to show that the car moved.

24. Section Check 1 1 Question 2 Displacement includes your __________ as well as the ___________ in which you have traveled. distance direction

25. Section Check 1 1 Question 3 Speed equals distance divided by _______. A. force B. mass C. time D. velocity

26. Section Check 1 1 Answer The answer is C – Time or t The smaller the t value in s = d/t the greater the speed.

27. Velocity of an object includes not only _______ but also_________ Question 4 speed direction

28. When writing the speed how do you write the units? A. Speed = 20 Miles + hours B. S = 20 kilometers + hours C. S = 20 km + hours D. S = 20 km/hr Question 5 Section Check

29. The answer is D. 20 km/hr Always use the units for time and distance that are given in the problem Answer

30. You went hiking at Sleeping Giant. The whole hike was 3.4 miles and it took you 30 minutes to get to the top. What was your speed? Question 6 Section Check

31. Answer Answer Speed = d/t Speed = ------ = You walked at a leisurely, relaxing pace 3.4 30 0.11 mi/min Section Check

32. Question 7 Question 7 When your speed remains the same during the entire hike, it is called? A. Average Speed B. Velocity C. Constant Speed D. Instantaneous Speed Section Check

33. Answer Answer The answer is C. Constant Speed Section Check