AP® Precalculus · Free response

A Ferris wheel seat

write it first, then score yourself point by point

Q3: Modeling a Periodic Context · Part B: no calculator · 6 points

The question

Name: ______________________   Date: ____________   A Ferris wheel seat (6 points)

Graph

Height of a Ferris wheel seat

A Ferris wheel has a diameter of 40 meters, and its center is 25 meters above the ground. The wheel turns counterclockwise at a constant speed and completes one full turn every 8 minutes. At time t=0t = 0 minutes, seat SS is at the lowest point of the wheel. The sinusoidal function hh models the height of seat SS above the ground, in meters, at time tt. The graph of hh for one full turn is shown with its axes unscaled. The points FF, GG, JJ, KK and MM are on the graph: FF, JJ and MM are a lowest or highest point, and GG and KK are at the height of the center of the wheel.
Left: a Ferris wheel on a support above the ground, turning counterclockwise, with a seat S at the lowest point of the wheel, which is above the ground. Right: an unscaled graph of h(t), the height of the seat above the ground, for one turn. The graph starts at its lowest point F, rises through G to its highest point J, falls through K and ends at the lowest point M. G and K are at the height of the center of the wheel. The axes have no scale.
LevlPrep original diagram.
  1. (A) Find the coordinates of the points FF, GG, JJ, KK and MM. [2 points]

  2. (B) The function hh is given by h(t)h(t)=asin⁡(b(t+c))+d= a\sin(b(t + c)) + d, where aa, bb, cc and dd are constants. Find values of aa, bb, cc and dd. [2 points]

  3. (C(i)) Is hh increasing or decreasing on the interval (2,4)(2, 4)? Give a reason for your answer in the context of the problem. [1 point]

  4. (C(ii)) Is the rate of change of hh increasing or decreasing on the interval (2,4)(2, 4)? Explain your reasoning. [1 point]