Unit 1 Lesson 1 Copyright © Houghton Mifflin Harcourt Publishing Company

Location, location, location Unit 1 Lesson 1 Motion and Speed Location, location, location How can you describe the location of an object? Position describes the location of an object. Comparisons using known objects or locations often are used to describe position. A reference point is a location to which you compare other locations. Copyright © Houghton Mifflin Harcourt Publishing Company 2

MOVE It! What is motion? Motion is a change in position over time. Unit 1 Lesson 1 Motion and Speed MOVE It! What is motion? Motion is a change in position over time. Even when motion is not observed directly, starting points and end points can indicate motion has occurred. Copyright © Houghton Mifflin Harcourt Publishing Company 3

How is distance measured? Unit 1 Lesson 1 Motion and Speed How is distance measured? Distance can be measured as a straight line between two positions. Distance can also be measured as the total length of a certain path between two positions. The standard unit of length for distance is the meter (m). Copyright © Houghton Mifflin Harcourt Publishing Company 4

Unit 1 Lesson 1 Motion and Speed What is speed? Speed is a measure of how far something moves in a given amount of time. Speed measures how quickly or slowly an object changes its position. Fast objects move farther than slower objects in the same amount of time. Copyright © Houghton Mifflin Harcourt Publishing Company 5

Unit 1 Lesson 1 Motion and Speed What is average speed? Average speed is a way to calculate the speed of an object that may not always be moving at a constant speed. Average speed describes the speed over a stretch of time rather than at any exact moment in time. Copyright © Houghton Mifflin Harcourt Publishing Company 6

Speed It Up! How is average speed calculated? Unit 1 Lesson 1 Motion and Speed Speed It Up! How is average speed calculated? Speed can be calculated by dividing the distance an object travels by the time it takes to cover that distance. speed = distance/time s = d/t Copyright © Houghton Mifflin Harcourt Publishing Company 7

How is average speed calculated? Unit 1 Lesson 1 Motion and Speed How is average speed calculated? If two objects travel the same distance, the object that takes less time has the greater speed. An object with a greater speed travels farther in the same time than an object with a lower speed travels. The standard unit for speed is meters per second (m/s). Copyright © Houghton Mifflin Harcourt Publishing Company 8

Fast Graphs How is constant speed graphed? Unit 1 Lesson 1 Motion and Speed Fast Graphs How is constant speed graphed? Distance-time graphs are used to plot the distance an object travels over time. The distance of an object away from a reference point is plotted on the y-axis. Time is plotted on the x-axis. Objects moving at a constant speed make a straight line on the graph. Copyright © Houghton Mifflin Harcourt Publishing Company 9

How is constant speed graphed? Unit 1 Lesson 1 Motion and Speed How is constant speed graphed? The slope, or steepness, of the line is equal to the average speed of the object. Average speed can be calculated by dividing the change in distance by the change in time for that time interval. slope = change in y/change in x Copyright © Houghton Mifflin Harcourt Publishing Company 10

How are changing speeds graphed? Unit 1 Lesson 1 Motion and Speed How are changing speeds graphed? On a distance-line graph, a change in the slope of a line indicates a change in speed. If the line gets steeper, the object’s speed has increased. If the line gets less steep, the object has slowed down. A flat line indicates zero speed. Copyright © Houghton Mifflin Harcourt Publishing Company 11

Follow Directions What is velocity? Unit 1 Lesson 1 Motion and Speed Follow Directions What is velocity? A vector is a quantity that has both size and direction. Velocity is speed in a specific direction. Objects can have the same speed but different velocities because of their direction of travel. Copyright © Houghton Mifflin Harcourt Publishing Company 12

Unit 1 Lesson 1 Motion and Speed What is velocity? Average velocity depends on the distance from the starting point to the final point. Average velocity can be 0 km/h if you travel at a certain speed to one point and then travel back to the starting point. Copyright © Houghton Mifflin Harcourt Publishing Company 13

Acceleration Unit 1 Lesson 2 Copyright © Houghton Mifflin Harcourt Publishing Company

Getting up to Speed How do we measure changing velocity? Unit 1 Lesson 2 Acceleration Getting up to Speed How do we measure changing velocity? Acceleration is the rate at which velocity changes. An object accelerates if its speed, direction, or both change. Acceleration depends on how much velocity changes and how much time that change takes. Copyright © Houghton Mifflin Harcourt Publishing Company 15

How do we measure changing velocity? Unit 1 Lesson 2 Acceleration How do we measure changing velocity? What is the change in velocity for each second of time that passes? Copyright © Houghton Mifflin Harcourt Publishing Company 16

How is average acceleration calculated? Unit 1 Lesson 2 Acceleration How is average acceleration calculated? Average acceleration = (final velocity – starting velocity)/time a = (v2 – v1)/t Acceleration is measured in meters per second squared (m/s2). Copyright © Houghton Mifflin Harcourt Publishing Company 17

What a Drag! How can accelerating objects change velocity? Unit 1 Lesson 2 Acceleration What a Drag! How can accelerating objects change velocity? Acceleration refers to both increases and decreases in speed. A change in direction is also acceleration. An increase in velocity is called positive acceleration. A decrease in velocity is called negative acceleration. Copyright © Houghton Mifflin Harcourt Publishing Company 18

How can accelerating objects change velocity? Unit 1 Lesson 2 Acceleration How can accelerating objects change velocity? Is the horse showing negative acceleration or positive acceleration? Explain. Copyright © Houghton Mifflin Harcourt Publishing Company 19

How can accelerating objects change velocity? Unit 1 Lesson 2 Acceleration How can accelerating objects change velocity? An object traveling in a circular motion is always changing its direction, and so it always experiences acceleration. Centripetal acceleration is acceleration in a circular motion. Copyright © Houghton Mifflin Harcourt Publishing Company 20