Introduction to Motion Essential Questions How do motion

Introduction to Motion

Essential Questions • • • How do motion diagrams represent motion? How can you use a particle model to represent a moving object? What is a coordinate system? How does the chosen coordinate system affect the sign of objects’ positions? What is displacement? How are motion diagrams helpful in answering questions about an object’s position or displacement? Copyright © Mc. Graw-Hill Education

Vocabulary Review • dimension Copyright © Mc. Graw-Hill Education New ● ● ● motion diagram particle model coordinate system origin position distance magnitude vector scalar time interval displacement resultant

All Kinds of Motion • When an object is in motion, its position changes. • Its position can change in many ways, including – straight line – a circle – back-and-forth vibration • A description of motion relates to place and time. • List and describe several examples of motion from your own experience. Copyright © Mc. Graw-Hill Education

Motion Diagrams and Particle Models • A series of images showing the positions of a moving object at equal time intervals is called a motion diagram. • In a particle model, you replace the object or objects of interest with single points. Copyright © Mc. Graw-Hill Education

Motion Diagrams and Particle Models Concepts in Motion Copyright © Mc. Graw-Hill Education

Coordinate Systems • A coordinate system tells you the location of the zero point of the variable you are studying and the direction in which the values of the variable increase. • The origin is the point at which both variables have the value zero. Copyright © Mc. Graw-Hill Education

Coordinate Systems • Consider a runner on this coordinate system. • You can indicate how far away an object is from the origin at a particular time by drawing an arrow from the origin to the object. • The two arrows locate the runner’s position at two different times. • Position is the distance and direction from the origin to the object. Copyright © Mc. Graw-Hill Education

Vectors and Scalars • Quantities that have both size (also called magnitude) and direction are called vectors. • Vectors can be represented by arrows. – Position is an example of a vector. It is represented by the symbol x. x 1 Copyright © Mc. Graw-Hill Education x 2

Vectors and Scalars • A quantity that is just a number without any direction is a scalar. • Examples of scalars: – Time – Distance – Temperature • Is mass a scalar? Explain. – Yes. Mass has a magnitude, but no direction. Copyright © Mc. Graw-Hill Education

Vectors and Scalars • The difference between two times is called a time interval. • Time intervals are scalars. • The time interval is defined mathematically as follows: • ∆ is the Greek letter delta. It is used to represent a change in a quantity. Copyright © Mc. Graw-Hill Education

Vectors and Scalars • A change in position is called a displacement. • Displacement is a vector. It is drawn with its tail at the earlier position and its tip at the later position. • Displacement can be represented mathematically as ∆x = xf − xi xf xi ∆x Copyright © Mc. Graw-Hill Education

Vectors and Scalars • A vector that represents the sum of two other vectors is called a resultant. • Example of Vector Addition Copyright © Mc. Graw-Hill Education

Vectors and Scalars • Example of Vector Subtraction Copyright © Mc. Graw-Hill Education

Vectors and Scalars • Example of Vector Subtraction Copyright © Mc. Graw-Hill Education

Review Essential Questions • • • How do motion diagrams represent motion? How can you use a particle model to represent a moving object? What is a coordinate system? How does the chosen coordinate system affect the sign of objects’ positions? What is displacement? How are motion diagrams helpful in answering questions about an object’s position or displacement? Vocabulary ● ● coordinate system origin position distance Copyright © Mc. Graw-Hill Education ● ● magnitude vector scalar motion diagram ● ● time interval displacement resultant particle model