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Formative assessment questions for teaching physics

A2L Item 146

  • Description: Identify the correct behavior of a body subject to the given potential energy function.
  • Goal: Hone the concept of potential energy functions
  • Source: UMPERG-ctqpe65
  • Keywords: Mechanics, Potential Energy

The question for students:

The potential energy function for a certain body is shown at right. If the body is released from rest at a location corresponding to point 4, the object would …

  1. move towards larger values of x.
  2. move towards smaller values of x.
  3. remain stationary.
  4. oscillate back and forth.
  5. None of the above
  6. Cannot be determined

Commentary for teachers:

Answer

(2) At position 4 the object experiences a force toward the origin given by the negative of the slope of the potential curve. Frequently students interpret the fact that U is zero at point 4 to mean that there is no force.