Energy Transformations

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Energy Transformations

• 8.01
• Week 05D3

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Next Reading Assignment W06D2

• Young and Freedman 8.1-8.5

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Group Problem Spring Gun

• A small block of mass m is pushed against a
  spring with spring constant k and held in place
  with a catch. The spring compresses an unknown
  distance x. When the catch is removed, the block
  leaves the spring and slides along a frictionless
  circular loop of radius r. When the block reaches
  the top of the loop, the force of the loop on the
  block (the normal force) is equal to twice the
  gravitational force on the mass. How far was the
  spring compressed?

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Group Problem Ball on String

• A ball of mass m is attached to point a by a
  string of length L. The ball is held out
  horizontally as shown in the figure, then
  released from rest and allowed to fall. When the
  string becomes vertical it impinges on a fixed
  peg at point b and the mass begins circular
  motion about that point. What is the minimum
  distance D between points a and b necessary to
  allow the mass to pass above b while still on a
  circular path? Note that the alternative is for
  the string to go slack before the mass passes the
  line between a and b.

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Mini-Experiment Two Peg Wrap
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Table Problem Potential Energy Diagram

• A body of mass m is moving along the x-axis. Its
  potential energy is given by the function U(x)
  b(x2-a2) 2 where b 2 J/m4 and a 1 m .
• a) On the graph directly underneath a graph of U
  vs. x, sketch the force F vs. x.
• b) What is an analytic expression for F(x)?

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Next Reading Assignment W06D2

• Young and Freedman 8.1-8.5