1. Motion Describing and Measuring Motion Slow Motion on Planet Earth Acceleration Table of Contents

2. Motion - Describing and Measuring Motion Describing Motion Whether or not an object is in motion depends on the reference point you choose.

3. Motion - Describing and Measuring Motion Measuring Distance You can measure distances shorter than 1 meter in centimeters. The wingspan of the butterfly is 7 cm.

4. Motion Converting Units Use a conversion factor to convert one metric unit to another. A conversion factor is a fraction in which the numerator and denominator represent equal amounts in different units. Multiply the number you want to convert by the conversion factor. Suppose you want to know how many millimeters (mm) are in 14.5 meters (m). Since there are 1,000 millimeters in 1 meter, the conversion factor is: 1,000 mm/1 m Multiply 14.5 meters by the conversion factor to find millimeters. 14.5 m X 1,000 mm/1 m = 14.5 X 1,000 mm = 14,500 mm - Describing and Measuring Motion

5. Motion Converting Units Practice Problem How many centimeters are in 22.5 meters? 22.5 m = 2,250 cm - Describing and Measuring Motion

6. Motion - Describing and Measuring Motion Calculating Speed If you know the distance an object travels in a certain amount of time, you can calculate the speed of the object.

7. Motion - Describing and Measuring Motion Graphing Motion You can show the motion of an object on a line graph in which you plot distance versus time.

8. Motion What You Know What You Learned Using Prior Knowledge Before you read, write what you know about motion in a graphic organizer like the one below. As you read, write what you learn. 1.A moving object changes position. 2.Objects move at different speeds. 1.Motion is compared to a reference point. 2.The SI unit of length is the meter. - Describing and Measuring Motion

9. Motion End of Section: Describing and Measuring Motion

10. Motion Earth’s Plates According to the theory of plate tectonics, Earth’s landmasses have changed position over time because they are part of plates that are slowly moving. - Slow Motion on Planet Earth

11. Motion - Acceleration Calculating Acceleration To determine the acceleration of an object moving in a straight line, you must calculate the change in speed per unit of time.

12. Motion Position, Velocity, Acceleration SymbolUnitWord equationEquation in Symbols Positionxm Velocityvmsms velocity = change in position change in time Accelerationams2ms2 acceleration = change in velocity change in time

13. Motion Calculating Acceleration As a roller-coaster car starts down a slope, its speed is 4 m/s. But 3 seconds later, at the bottom, its speed is 22 m/s. What is its average acceleration? Read and Understand What information have you been given? Initial speed = 4 m/s Final Speed = 22 m/s Time = 3 s - Acceleration

14. Motion Calculating Acceleration As a roller-coaster car starts down a slope, its speed is 4 m/s. But 3 seconds later, at the bottom, its speed is 22 m/s. What is its average acceleration? Plan and Solve What quantity are you trying to calculate? The average acceleration of the roller-coaster car = __ What formula contains the given quantities and the unknown quantity? Acceleration = (Final speed – Initial speed)/Time Perform the calculation. Acceleration = (22 m/s – 4 m/s)/3 s = 18 m/s/3 s Acceleration = 6 m/s 2 The roller-coaster car’s average acceleration is 6 m/s 2. - Acceleration

15. Motion Calculating Acceleration As a roller-coaster car starts down a slope, its speed is 4 m/s. But 3 seconds later, at the bottom, its speed is 22 m/s. What is its average acceleration? Look Back and Check Does your answer make sense? The answer is reasonable. If the car’s speed increases by 6 m/s each second, its speed will be 10 m/s after 1 second, 16 m/s after 2 seconds, and 22 m/s after 3 seconds. - Acceleration

16. Motion Calculating Acceleration Practice Problem A falling raindrop accelerates from 10 m/s to 30 m/s in 2 seconds. What is the raindrop’s average acceleration? (30 m/s – 10 m/s) ÷ 2 seconds = 10 m/s 2 - Acceleration

17. Motion Calculating Acceleration Practice Problem A certain car can accelerate from rest to 2.7 m/s in 9 seconds. Find the car’s average acceleration. (27 m/s – 0 m/s) ÷ 9 s = 27 m/s ÷ 9 s = 3 m/s 2 - Acceleration

18. Motion Graphing Acceleration You can use both a speed-versus-time graph and a distance- versus-time graph to analyze the motion of an accelerating object. - Acceleration

19. Motion Main Idea Detail Identifying Main Ideas As you read the section “What is Acceleration?”, write the main idea in a graphic organizer like the one below. Then write three supporting details that further explain the main idea. In science, acceleration refers to... Increasing speedDecreasing speed Changing direction - Acceleration

20. Motion End of Section: Acceleration

21. Motion Graphic Organizer Reference point Motion is described relative to a Distance ÷ Time SpeedVelocity is measured by equals in a given direction is called

22. Motion End of Section: Graphic Organizer