Chapter 2: Representing Motion

Pg. 30

Launch Lab/demonstration

• What data did you collect to show which car was faster?

• What other data could you collect to determine which car is faster

Put toys into motion categories

• How would you categorize these toys based on motion?

Motion

• How do you know something is moving?

• What evidence would it take to convince them that something is moving?

Frame of Reference and Reference Points

• What is frame of reference?

• What is a reference point? (show video from online activity)

Various kinds of motion

• Throwing a touchdown football pass• Bowling • Bicycle wheel going around in a circle

Where do we start in physics???

Linear Movement

• Movement in a straight line is the most basic• Sometimes represent motion in a motion

diagram• Draw a motion diagram and particle model

below

Coordinate Systems pg. 34

• How do you explain to get to your house to someone who is not from town.

• What reference points did you use to explain where you house is?

Coordinate Systems

• Coordinate system

• Origin

• Position

• distance

Position does not equal Distance

• How are they different??? Examples-

Vectors and scalars

• Magnitude

• Vector

• Scalar

• Resultant Adding vectors = place them tip to tail

Tinkering with vectors lab

• Materials (lumps of clay/play do and straws)

Distance and Displacement

• Are they the same???

• Think about going from this classroom to the library, how many possible ways can you get from here to there?

• Are all the ways the same distance?• Do you have the same displacement?

Time Interval & Displacement

• ∆t = tf – ti

The time interval is equal to the final time minus the initial time

• ∆d = df – di

Displacement is equal to the final position minus the initial position

Subtracting Vectors

• A – B = A + (-B)

• Draw the figure in textbook

Position vs. Time graphs 2.3

• Pg. 39 Practice Problems (9-13)

Instantaneous position

• The position at a particular instant

Practice problems pg. 41

• Note: At what time do A and B have the same position?

• Why did you start the origin at where you did? What would happen if you choose runner B’s start as the origin; what would A position be?

• 14-18

How Fast???

• Watch-They Might Be Giants “Speed vs. Velocity”

• What is speed; what is velocity?

Average Velocity

• Average Velocity

• Calculate average velocity from figure 2-20 on page 43.

Practice problems pg. 45