posted by Anonymous .
A fountain in a shopping centre has a single jet of water. The height of the jet of water varies according to a sinusoidal function. A student notes that, in exactly one minute, the jet goes from a minimum height of 2m to a maximum height of 6m and back to 2m.
At 13:00, the jet of water is at a height of 2m.
What will be the height of the jet of water, to the nearest tenth of a metre, when the clock reads 13:12:40? (13hr, 12min, 40sec). Thanks a lot!
F = 1c/min = 1rev/min. = Frquency.
P = 1/F = 1min/rev. = The period.
T = 13:12:40 - 13:0:0 = 12min,40s. =
12 2/3 min. = 38/3 min.
1rev/min * (38/3)min = 12 2/3 rev.
(2/3)rev * 360Deg/rev = 240 Deg.
Ar=240-180 = 60 Deg.=Reference angle.
h = hmax*sinAr = 6*sin60 = 5.2 m.