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