Simple Harmonic Motion (1 Viewer)

[Lukybear]

The rise and fall of the tide approximate SHM. Suppose the interval between sucessive high tides in a certain harbour is 12 hours 30 minutes and that in the entrance the depth of water at high tide is 10m and at low tide is 6 m. If on a certain day low tide occurs at 6 am at what time will the depth of water in the harbour entrance first reach 9m

 

[shaon0]

The rise and fall of the tide approximate SHM. Suppose the interval between sucessive high tides in a certain harbour is 12 hours 30 minutes and that in the entrance the depth of water at high tide is 10m and at low tide is 6 m. If on a certain day low tide occurs at 6 am at what time will the depth of water in the harbour entrance first reach 9m

A=2, T=12.5hrs => n=2pi/(12.5).
f=-Acos(@)+B
=-2cos( (4pi/25)t)+8,
is your equation (i think) but i can't really remember useless maths from HSC.
9=-2cos((4pi/25)t)+8
-1/2=cos((4pi/25)t)
2pi/3=(4pi/25)t
50/12=t
Thus, Time is 6+50/12=10+1/6=10:10am