What did you learn this week Why do you believe in it

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What did you learn this week? Why do you
believe in it?
PERC 2003
Rutgers University Eugenia Etkina
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What is ISLE?

• Students learn physics using the same strategies
  that physicists use to construct their knowledge.
  
• Strategies include
• Making observations and discovering patterns
• Developing and testing models
• Applying models
• Methods used by students
• construct and use multiple representations of
  physical processes
• solve multipart problems
• design investigations
• constantly reflect on knowledge construction

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ISLE Cycle
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Weekly Reports

• 1. What did you learn this week?
• 2. Why do you believe in it?
• 3. What remained unclear?
• 4. What questions would you ask if you were the
  professor to find out whether your students
  understood the material?

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What is Extended Analytical Physics?

• Extended Analytical Physics (EAP) is an
  introductory physics course for at-risk
  engineering students that provides an alternate
  path in the first year.

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Engineering Physics Options
2nd Year Electromagnetism, Optics, Modern Physics
1st Year Mechanics, Waves, and Thermodynamics
Extended Analytical Physics (EAP I) 3 credits
per semester
Extended Analytical Physics II (AP II) 3 credits
per semester
Analytical Physics (AP I) 2 credits per semester
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ISLE in Extended Analytical Physics
                     
 
Recitation Hands-On Activities for Chapter n
-Developing Model -Testing Model  
Recitation HW due for Chapter n -Application
Problems  

• Lecture Activities
• -Testing Model w/ Experiments and Problems
• -Application of
• Model

 
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Miscellaneous Examples of Activities I

• Making Observations
• Measuring spring extension for different masses
  on a vertical spring
• Measuring necessary pulling force to move various
  masses of blocks with friction
• Measuring position and time data for different
  1-d motions
• Discovering Patterns
• Plotting data on board and looking for best-fit
  function
• W vs Dx for ideal vertical spring
• x vs t for different motions

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Miscellaneous Examples of Activities II

• Developing Model
• Vertical and horizontal motions are independent
  in projectile motion
• Frictional force is independent of surface area
• Testing Model
• Predicting where projectile lands
• Predicting the reading of a spring scale
• Applying Model
• Designing method to measure coefficient of
  friction without a spring
• Solve Atwood machine problems experimentally

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One Cycle UCMObservations

• Lecturer hits bocce ball with a baton such that
  the ball moves in UCM
• Conceptual Model
• If the net force is uniform and points toward the
  center of the circle the ball will continue with
  UCM

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One Cycle UCMDevelop Mathematical Model

• Three circle conceptual development.
• Mathematical Model If the net force is uniform
  and points toward the center of the circle and is
  proportional to v2/r then the ball will continue
  with UCM

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One Cycle UCMTesting Conceptual Model

• What if Fnet stops being centripetal?
• If Fnet is not centripetal then the motion stops
  being UCM

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What did I learn this week?

• Circular motion was also covered- centripetal
  force is what pulls the object to the center
  keeping it from flying off at a tangent to the
  circle and centrifugal force is a false force-
  the one that feels like its pushing out on the
  object-a person crashing into a car door after a
  sharp turn exerts force on the door even though
  in reality this is just a product of friction not
  being able to exert the needed centripetal force
  on the person- thus the person is flying off the
  rotation as the car stays in it.

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One Cycle UCMTesting Mathematical Model

• Conical Pendulum
• Calculate a and q by measuring v, r and L.
• Determine the radial tension necessary to cause
  this acceleration (measure mass).
• Stop the motion, pull the bob into a static
  position at q using a force probe.
• Compare force probe reading to the
  measured/calculated Tradial.

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One Cycle UCM Applying the Model

• Record player and rubber stopper
• Turn on record player with rubber stopper near
  center
• Turn off record player and move the stopper to
  the edge. acceleration (measure mass).
• Turn on record player with rubber stopper at the
  edge
• Describe what happens and explain why it happens.

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How did you learn it?

• We did an experiment with an old turntable and
  an object on top of it. The object would remain
  still relative to the spinning turntable at small
  radii and when the radii was increased the
  object would fly off... static frictional force
  was no longer great enough to hold the object
  there. The only force present in the free body
  diagram of the object in the radial direction was
  the frictional force, so we thus concluded that
  the frictional force must be creating the
  centripetal force.