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At the amusement park, you decide to ride the Ferris wheel, which has a maximum height of 80 meters and a diameter of 40 meters...Asked by kate
At the amusement park, you decide to ride the Ferris wheel, which has a maximum height of 100 meters and a diameter of 50 meters. It takes the wheel seven minutes to make one revolution. Write the sinusoidal function, f(t), that models the height of your chair at any time,
Answers
Answered by
Reiny
we know a = 50, and the period is 7 minutes
2π/k = 7
k = 2π/7
then let's start with the basic shape of
height = 50sin (2π/7)t , where t is in minutes and height is in metres.
but the maximum height is 100 m , so we have to raise our curve 50 m
height = 50sin (2π/7)t + 50
but we probably want our height to be zero when t = 0, so we need a phase shift
height = 50sin(2π/7)(t+d) + 50
50sin(2π/7)(d) + 50 = 0
sin (2π/7)(d) = -1
we know sin 3π/2 = -1 , so
(2π/7)(d) = 3π/2
d = (3π/2)(7/2π) = 21/4
height = 50 sin (2π/7)(t + 21/4) + 50
check:
if t = 0, height = 0 , check!
if t = 1.75, height = 50
if t = 3.5, height = 100
if t = 5.25 , height = 50
if t = 7 , height = 0, all checks out
f(t) = 50 sin ( (2π/7)(t + 21/4) ) + 50
confirmation:
www.wolframalpha.com/input/?i=plot+y+%3D+50+sin+(+(2%CF%80%2F7)(x+%2B+21%2F4)+)+%2B+50
2π/k = 7
k = 2π/7
then let's start with the basic shape of
height = 50sin (2π/7)t , where t is in minutes and height is in metres.
but the maximum height is 100 m , so we have to raise our curve 50 m
height = 50sin (2π/7)t + 50
but we probably want our height to be zero when t = 0, so we need a phase shift
height = 50sin(2π/7)(t+d) + 50
50sin(2π/7)(d) + 50 = 0
sin (2π/7)(d) = -1
we know sin 3π/2 = -1 , so
(2π/7)(d) = 3π/2
d = (3π/2)(7/2π) = 21/4
height = 50 sin (2π/7)(t + 21/4) + 50
check:
if t = 0, height = 0 , check!
if t = 1.75, height = 50
if t = 3.5, height = 100
if t = 5.25 , height = 50
if t = 7 , height = 0, all checks out
f(t) = 50 sin ( (2π/7)(t + 21/4) ) + 50
confirmation:
www.wolframalpha.com/input/?i=plot+y+%3D+50+sin+(+(2%CF%80%2F7)(x+%2B+21%2F4)+)+%2B+50