Chapter 2: Representing Motion Pg. 30
Dec 26, 2015
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