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Catalyst. v f - v i. a. =. The equation for acceleration is 1. A lizard accelerates from 2 m/s to 10 m/s in 4 seconds. What is the lizard’s average acceleration ?
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Catalyst vf - vi a = • The equation for acceleration is • 1. A lizard accelerates from 2 m/s to 10 m/s in 4 seconds. What is the lizard’s average acceleration? • 2. If a Ferrari, with an initial velocity of 10 m/s, accelerates at a rate of 50 m/s/s for 3 seconds, what will its final velocity be? • 3. What three things can you do to accelerate? t
Motion Graphs • There are THREE types: • Position vs. Time • Gives your position over a period of time. • Velocity vs. Time • Gives your speed (velocity) over a period of time. • Acceleration vs. Time • Gives your acceleration over a period of time.
Position vs. Time Graphs • We’ve seen these before! • Slope is velocity(or speed) • Straight lines mean constant velocity
Position vs. Time Graphs • Curved lines mean acceleration • Cannot find slope of curved lines
Position vs. Time Graphs • Horizontal (flat) lines mean no motion • Constant position
Position vs. Time Graph Demonstration • http://zonalandeducation.com/mstm/physics/mechanics/kinematics/xvaVsTime/xVsTime.html
Velocity vs. Time Graphs • These are new! • Slope is acceleration • Straight lines mean constant acceleration
Velocity vs. Time Graphs • Curved lines mean changingacceleration • Cannot find slope of curved lines
Velocity vs. Time Graphs • Horizontal (flat) lines mean no acceleration or constant speed
Velocity vs. Time Graph Demonstration • http://www.physicsclassroom.com/mmedia/kinema/fs.cfm
Acceleration vs. Time Graphs • Flat lines mean constant acceleration • Everything else means nothing! (for our purposes) • The only other acceleration vs. time graph you will see is this: • Which means no acceleration
Example: No Motion Position vs. Time Velocity vs. Time Acceleration vs. Time
Example: Constant Velocity Position vs. Time Velocity vs. Time Acceleration vs. Time
Example: Constant Acceleration = Object is Speeding Up Position vs. Time Velocity vs. Time Acceleration vs. Time
Guided Practice #1-2 • Which of the objects on each graph at right is accelerating? How do you know?
Guided Practice #3 • At which point is velocity (speed) the greatest? • At which point is velocity (speed) the least? • At which points is acceleration occurring?
Guided Practice #4 • At which point is velocity the greatest? • At which point is velocity the least? • At which points is acceleration occurring? • Where is acceleration the least?
Exit Slip 1. What would the velocity vs. time graph look like for a car going straight on a highway at constant speed? • A horizontal (flat) line • A straight line that is increasing • A straight line that is decreasing • A curved line that is increasing 2. What does a straight line with a positive slope mean on a velocity vs. time graph? • Increasing velocity • Constant acceleration • Constant velocity • Both A and B
Exit Slip 3. True or false: Constant acceleration means that the object is speeding up. 5. For which graph does a horizontal (flat) line always mean that the object is motionless? • Position vs. time • Velocity vs. time • Acceleration vs. time • Both A and C