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FRAMES

FRAMES. OF. Reference. Pass out the Frames of Reference notes. 11/5/09. Have you ever, in a car wash… jammed your foot on the brake when you felt the car moving and then felt foolish when it wasn’t. 11/5/09. Have you ever …

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FRAMES

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  1. FRAMES OF Reference

  2. Pass out the Frames of Reference notes 11/5/09

  3. Have you ever, in a car wash… jammed your foot on the brake when you felt the car moving and then felt foolish when it wasn’t. 11/5/09

  4. Have you ever … thrown a ball up while riding in a car or bus and wondered how it looked from outside the car or bus? 11/5/09

  5. Have you ever, while stopped at a stoplight … jammed your foot on the brake when you felt the car moving and then felt foolish when it wasn’t. 11/5/09

  6. Play the video… “FRAMES OF REFERENCE” Only play from 0:00 to 3:15 Works best in Quicktime 11/5/09

  7. Newton’s Law of motion holds equally well whether a reference frame is not moving at all…. or moving with constant velocity These reference frames are called inertial reference frames. 11/5/09

  8. When are you in an inertial frame of reference? If you are not moving or moving with a constant velocity. 11/5/09

  9. Play the video… “FRAMES OF REFERENCE” Now play from 3:15 to 9:58 Works best in Quicktime 11/5/09

  10. Let’s introduce a new way of naming velocities Label for reference frame (g = ground) Vmg Label for object (m = man) 11/5/09

  11. Let’s learn how to add relative velocities To solve for a specific velocity, you must use other relative velocities to find your answer. Set up an equation so that the outer subscripts are the same as your final answer. Then just do the math. Sometimes this is simply addition, later we see this may involve a triangle.) Vpm +Vmg = Vpg Vpm +Vmg = Vpg notice these are both m’s 11/5/09

  12. Let’s learn how to add relative velocities To solve for a specific velocity, you must use other relative velocities to find your answer. Set up an equation so that the outer subscripts are the same as your final answer. Then just do the math. Sometimes this is simply addition, later we see this may involve a triangle.) Vpm +Vmg = Vpg (5 m/s)+ (2 m/s) = Vpg 7 m/s = Vpg You may have noticed the puck moved quite rapidly 11/5/09

  13. Play the video… “FRAMES OF REFERENCE” Now play from 9:58 to 13:25 Works best in Quicktime 11/5/09

  14. Play the video… “FRAMES OF REFERENCE” Now play from 9:58 to 13:25 Works best in Quicktime 11/5/09

  15. End of Thursday’s notes…. End of Thursday’s notes…. 11/6/09

  16. HERE Begin Day Two Notes 11/5/09

  17. Play the DVD… “Physics Phun” Click on Kinematics Play Intro to Reference Frames 11/5/09

  18. Play the DVD… “Physics Phun” Click on Kinematics Play Relative Motion on a Train 11/5/09

  19. Have you ever... seen books sliding across the car seat as you hit your brakes? 11/6/09

  20. Play the video… “FRAMES OF REFERENCE” Now play from 13:25 to 17:04 Works best in Quicktime 11/5/09

  21. Newton’s laws work in an inertial frame of reference. They do not work in a non-inertial (accelerated) frame of reference. 11/6/09

  22. Have you ever... seen books sliding across the car seat or the dash as you turned a corner? 11/6/09

  23. Play the video… “FRAMES OF REFERENCE” Now play from 17:04 to END Works best in Quicktime 11/5/09

  24. Thinking back to this question, Have you ever seen books sliding across the car seat or the dash as you turned a corner? 11/6/09

  25. In the car’s reference frame, what is the force(s) acting on the books? There are none. Why not? We are using Newton’s laws in a non-inertial (accelerated) frame. 11/6/09

  26. If the reference frame is accelerating… Newton’s laws of motion do not work. 11/6/09

  27. Is the earth accelerating? If so then why do Newton’s laws work? The expected differences are too small to observe. 11/6/09

  28. Summary: Newton’s laws apply in inertial reference frames, but they do not apply in accelerated reference frames. 11/6/09

  29. Let’s learn how to add relative velocities in two dimensions Just like before we must use other relative velocities to find your answer. Set up an equation so that the outer subscripts are the same as your final answer. Now we must use a triangle to find a resultant. Vcs +Vsg = Vcg A canoe attempts to cross a stream, and the stream flows “upstream”. 11/5/09

  30. Let’s learn how to add relative velocities in two dimensions Just like before we must use other relative velocities to find your answer. Set up an equation so that the outer subscripts are the same as your final answer. Now we must use a triangle to find a resultant. Vcs +Vsg = Vcg If it’s a right triangle, Use the Pythagorean Theorem to find the resultant value. Use trig functions (sin, cos, tan) to find the angle. 11/5/09

  31. If there is time to review… Open this website http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=140.0 Hover the mouse over an object to change the frame of reference Click on info to see the relative velocities Again, change the frame of reference to see how the values (and sometimes direction) change 11/5/09

  32. If there is time to review… Open this website http://www.mrwaynesclass.com/teacher/ReferenceFrames/FrameOfRef.swf Play this short animation Determine which solution is best In fact, both are possible explanations for the motion of the stars and spaceship 11/5/09

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