Friday, 9/19Friday, 9/19 Pick handout from Physics binPick handout from Physics bin We are taking notes today…take out your We are taking notes today…take out your

notebook/paper and something to write notebook/paper and something to write with.with.

In your notes respond to the following (3 In your notes respond to the following (3 minutes):minutes):1. We have talked about velocity and its 1. We have talked about velocity and its components (distance and time). Use your components (distance and time). Use your drawing skills to describe velocity without drawing skills to describe velocity without numbers.numbers.2. We have talked about acceleration and its 2. We have talked about acceleration and its components (change in velocity and time). Use components (change in velocity and time). Use your drawing skills to describe acceleration. your drawing skills to describe acceleration.

Interpreting Interpreting Motion GraphsMotion Graphs

Two Types of GraphsTwo Types of Graphs

Position time graphsPosition time graphs Velocity time graphsVelocity time graphs

Position vs. time Position vs. time graphsgraphs The slope of the graph is The slope of the graph is

equal to the velocity equal to the velocity If the d/t graph is a straight If the d/t graph is a straight

line (no curve) then the line (no curve) then the velocity is constant.velocity is constant.

Reference Point….Reference Point….

Position vs. time Position vs. time graphsgraphs

A line with a positive A line with a positive slope indicates positive slope indicates positive velocity and the object velocity and the object is moving away from is moving away from the reference pointthe reference point

A line with a negative A line with a negative slope indicates negative slope indicates negative velocity and the object velocity and the object is moving towards the is moving towards the reference point.reference point.

Position vs. time Position vs. time graphsgraphs If the line is horizontal (no slope) then If the line is horizontal (no slope) then

the object is stationary (no velocity)the object is stationary (no velocity)

If the object is accelerating, If the object is accelerating, the velocity is the velocity is changingchanging

p/t graph will no longer be a p/t graph will no longer be a straight line, but will have a straight line, but will have a changing slope, resulting in a changing slope, resulting in a curve.curve.

Position vs. time Position vs. time graphsgraphs

Accelerated MotionAccelerated Motion

Position vs. time Position vs. time graphsgraphs Concave Concave ““Up like a cupUp like a cup””…the …the

acceleration is positiveacceleration is positive

Slowing down towards Speeding up away

Concave Concave ““Down like a frownDown like a frown””…the …the acceleration is negativeacceleration is negative

Position vs. time Position vs. time graphsgraphs

Slowing down away Speeding up towards

The The slopeslope is equal to the is equal to the accelerationacceleration. .

Velocity vs. time Velocity vs. time graphsgraphs

Velocity vs. time Velocity vs. time graphsgraphs Positive velocity indicates Positive velocity indicates

the object is moving the object is moving away from the reference away from the reference pointpoint

The x axis means v=0The x axis means v=0 Green is slower, getting Green is slower, getting

closer to zero.closer to zero. Purple is speeding up, Purple is speeding up,

moving farther from the x moving farther from the x axis.axis.

Negative velocity Negative velocity indicates the object is indicates the object is moving toward the moving toward the reference point.reference point.

Velocity vs. time Velocity vs. time graphsgraphs

Velocity vs. time Velocity vs. time graphsgraphs

(Acceleration)(Acceleration) When the When the

slope is zero:slope is zero:– horizontal horizontal

lineline– velocity is velocity is

constantconstant– acceleration acceleration

is zerois zero

Velocity vs. time Velocity vs. time graphsgraphs

When the slope When the slope of the graph is of the graph is positive:positive:– the acceleration the acceleration

is positiveis positive

Velocity vs. time Velocity vs. time graphsgraphs

When the slope When the slope of the graph is of the graph is negative:negative:– the the

acceleration is acceleration is negativenegative

We cannot determine We cannot determine where an objectwhere an object’’s s positionposition from a v/t from a v/t

graph, only its graph, only its changechange in position.in position.

Velocity vs. time Velocity vs. time graphsgraphs