Physics 31

Fall 2008

Information

• Homework Assignments made daily, but collected weekly on Wednesdays.

• Help session Tuesday evenings 6:00-8:30pm Room 127

• Motion diagrams

• Position and time

• Velocity

• Scientific notation and units

• Vectors and motion

Chapter 1Concepts of Motion and Mathematical BackgroundTopics:

Sample question:

As this snowboarder moves in a graceful arc through the air, the direction of his motion, and the distance between each of his positions and the next, is constantly changing. What language should we use to describe this motion?

Four Types of Motion We’ll Study

Making a Motion Diagram

Examples of Motion Diagrams

A simplifying model in which we treat the object as if all its mass were concentrated at a single point. This model helps us concentrate on the overall motion of the object.

The Particle Model

The position of an object is located along a coordinate system.

Position and Time

At each time t, the object is at some particular position. We are free to choose the origin of time (i.e., when t = 0).

Displacement

The change in the position of an object as it moves from initial position xi to final position xf is its displacement ∆x = xf – xi.

Slide 1-15

Speed

Slide 1-22

The car moves 40 m in 1 s. Its speed is = 40 .40 m

1 s

m

s

The bike moves 20 m in 1 s. Its speed is = 20 .20 m

1 s

m

s

Velocity

Slide 1-23

Homework

• Due Wednesday– Read Chapter 1: 1-5 Motion, Scientific

Notation, dimensions, vectors– Problems Ch. 1: CQ3, CQ4, CQ6, MC21, 3, 4

Help session tomorrow, Tuesday, August 26, room 127