2. Lesson 2: Describing Motion with Diagrams Introduction to Diagrams Throughout the course, there will be a persistent appeal to your ability to represent physical concepts in a visual manner. You are not limited to the use of words to describe the motion of objects. The use of graphs, the use of numbers, the use of equations, and the use of diagrams are all ways in which we can describe the motion of objects. Lesson 2 focuses on the use of diagrams to describe motion. The two most commonly used types of diagrams used to describe the motion of objects are: 1. Ticker tape diagram 2. Vector diagram

3. Lesson 2: Describing Motion with Diagrams Ticker Tape Diagrams The distance between dots on a ticker tape represents the object's position change during that time interval. A large distance between dots indicates that the object was moving fast during that time interval. A small distance between dots means the object was moving slow during that time interval. Ticker tapes for a fast- and slow-moving object are depicted below.

4. Lesson 2: Describing Motion with Diagrams Ticker Tape Diagrams The analysis of a ticker tape diagram will also reveal if the object is moving with a constant velocity or accelerating. A changing distance between dots indicates a changing velocity and thus an acceleration. A constant distance between dots represents a constant velocity and therefore no acceleration.

5. Brain Break The Shining

6. Lesson 2: Describing Motion with Diagrams Check Your Understanding Renatta Oyle owns a car that leaks oil and it leaves a signature of Renatta's motion wherever she goes. Describe Renatta's motion in terms of her velocity and acceleration during her trip. Velocity is negative (leftward) Velocity is changing (acceleration) Velocity is increasing (acceleration is leftward) Acceleration is negative (leftward)

7. Lesson 2: Describing Motion with Diagrams Vector Diagrams Vector diagrams are diagrams which depict the direction and relative magnitude of a vector quantity by a vector arrow. Vector diagrams can be used to describe the velocity of a moving object during its motion. For example, the velocity of a car moving down the road could be represented by a vector diagram.

8. Lesson 2: Describing Motion with Diagrams Test Your Knowledge Describe the motion, in terms of velocity and acceleration, of the ball as it travels up and then back down. -The ball’s acceleration is negative and constant both up and down. -The ball’s velocity decreases on the way up and increases on the way down.