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Starter Questions

Wednesday:The graph depicts the speed of two vehicles:1. Which line graph is the faster one?2. Which line graph is the slower one?

AB

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Velocity

V = velocity (meters/second)

d = distance (meters)t = time (seconds)

d

V =

tspeed of an object in acertain direction.

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How much time will ittake a car driving avelocity of 50 miles/hr

east to drive 300miles?

(Remember: t = v/d)

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How would you describe the motion offloating balloons?

Do they move in a constant speed or

direction?

The movement of a balloonis a great example of an object

Accelerating!

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Uniform Circular Motion

Figure 9 pg 329 Would a windmill traveling in a circle at a

constant speed be accelerating?

Direction; Are you accelerating, now?

http://www.pbs.org/opb/circus/classroom/circus-physics/activity-guide-centripetal-acceleration/

http://www.pbs.org/opb/circus/classroom/circus-physics/activity-guide-centripetal-acceleration/http://www.pbs.org/opb/circus/classroom/circus-physics/activity-guide-centripetal-acceleration/http://www.pbs.org/opb/circus/classroom/circus-physics/activity-guide-centripetal-acceleration/http://www.pbs.org/opb/circus/classroom/circus-physics/activity-guide-centripetal-acceleration/http://www.pbs.org/opb/circus/classroom/circus-physics/activity-guide-centripetal-acceleration/http://www.pbs.org/opb/circus/classroom/circus-physics/activity-guide-centripetal-acceleration/http://www.pbs.org/opb/circus/classroom/circus-physics/activity-guide-centripetal-acceleration/http://www.pbs.org/opb/circus/classroom/circus-physics/activity-guide-centripetal-acceleration/http://www.pbs.org/opb/circus/classroom/circus-physics/activity-guide-centripetal-acceleration/http://www.pbs.org/opb/circus/classroom/circus-physics/activity-guide-centripetal-acceleration/

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Accelerationhow quickly velocity changesover time.

A = (Vfinal - Vinitial )

time

___________

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Acceleration = A change in Velocity

][][

2 sm

TimeVelocityon Accelerati T A

V

You already learned theVelocity equation:

Here is the equation for Acceleration:

][][

sm

Timecetan Dis

Velocity

Means change

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Question

During a race, a runners velocityincreases from 0 m/s to 4 m/s over aperiod of 2 s. What is the bicyclesaverage acceleration during this period?

a= 4m/s-2m/s = ________m/s/s2s

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Constant Velocity

1 2 3 4 5

A characteristic of constant velocity is that all distances between seconds are

the same.

Time [Sec]

D i s t a n c e [ m

]

1s slow

1.2m

2s slow

2.4m

3s slow

3.6m

0 1 2 3 4 5

6

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Question

What would the graph look like for a carslowing down to a stop?

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Time

Interpreting Acceleration on a Graph

5 m

15 m

10 m

15 s10 s5 s

D i s

t a n c e

D i s

t a n c e

Positive

Acceleration in anegative direction

Negative Acceleration in a

Positive direction

Flat line = Novelocity, so noacceleration

http://onlinelearningexchange.com/texas_demo/grade8.html

http://onlinelearningexchange.com/texas_demo/grade8.htmlhttp://onlinelearningexchange.com/texas_demo/grade8.html

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Question

What kind of graph will a negativeacceleration produce?

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Time

Interpreting Acceleration on a Graph

5 m

15 m

10 m

15 s10 s5 s

D i s

t a n c e

D i s

t a n c e

Positive

Acceleration in anegative direction

Negative Acceleration in a

Positive direction

Flat line = Novelocity from thePOR

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Lesson Extensions

Falling Pumpkins http://www.physicsclassroom.com/mm

edia/vectors/mzs.cfm http://www.onlinemathlearning.com/velocit

y-acceleration.html http://dev.physicslab.org/Document.aspx?

doctype=5&filename=Kinematics_Uniform AccelerationVelocityTimeGraphs1.xml

Simon Says Accelerate

http://www.physicsclassroom.com/mmedia/vectors/mzs.cfmhttp://www.physicsclassroom.com/mmedia/vectors/mzs.cfmhttp://www.physicsclassroom.com/mmedia/vectors/mzs.cfmhttp://www.onlinemathlearning.com/velocity-acceleration.htmlhttp://www.onlinemathlearning.com/velocity-acceleration.htmlhttp://dev.physicslab.org/Document.aspx?doctype=5&filename=Kinematics_UniformAccelerationVelocityTimeGraphs1.xmlhttp://dev.physicslab.org/Document.aspx?doctype=5&filename=Kinematics_UniformAccelerationVelocityTimeGraphs1.xmlhttp://dev.physicslab.org/Document.aspx?doctype=5&filename=Kinematics_UniformAccelerationVelocityTimeGraphs1.xmlhttp://dev.physicslab.org/Document.aspx?doctype=5&filename=Kinematics_UniformAccelerationVelocityTimeGraphs1.xmlhttp://dev.physicslab.org/Document.aspx?doctype=5&filename=Kinematics_UniformAccelerationVelocityTimeGraphs1.xmlhttp://dev.physicslab.org/Document.aspx?doctype=5&filename=Kinematics_UniformAccelerationVelocityTimeGraphs1.xmlhttp://www.onlinemathlearning.com/velocity-acceleration.htmlhttp://www.onlinemathlearning.com/velocity-acceleration.htmlhttp://www.onlinemathlearning.com/velocity-acceleration.htmlhttp://www.onlinemathlearning.com/velocity-acceleration.htmlhttp://www.physicsclassroom.com/mmedia/vectors/mzs.cfmhttp://www.physicsclassroom.com/mmedia/vectors/mzs.cfmhttp://www.physicsclassroom.com/mmedia/vectors/mzs.cfmhttp://www.physicsclassroom.com/mmedia/vectors/mzs.cfmhttp://www.physicsclassroom.com/mmedia/vectors/mzs.cfmhttp://www.physicsclassroom.com/mmedia/vectors/mzs.cfm

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Acceleration

With Acceleration, Notice the differenceof distance with the red acceleration lines

between each second?

1sec

1 0m

2sec

3m

1 2