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Derivative applications challenge

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A 13 m ladder is leaning against a wall when its base begins to slide away from the wall. By the time the base is 12 m from the wall, it is moving at a rate of 5 m/s (meters per second).
At that moment, what is the vertical velocity of the top of the ladder?
Your answer should be negative since the top of the ladder is falling.
  • Your answer should be
  • an integer, like 6
  • an exact decimal, like 0.75
  • a simplified proper fraction, like 3/5
  • a simplified improper fraction, like 7/4
  • a mixed number, like 1 3/4