# Homework Help: Problem for math class

1. Nov 12, 2009

### tennistudof09

We have this problem for math class:

For an interval of 45 minutes, the tsunamis near Hawaii caused by the chilean earthquake of 1960 could be modeled by the equation y= 8 sin (pi/6)t, where y is in feet and t is in minutes.

a) find the amplitude and period of the waves b) If the distance from one crest of the wave to the next was 21 kilometers, what was the velocity of the wave?

I know the amplitude is 8 and 2pi/ (pi/6) came out to be 12, so I got 12 for the period. For question b, in order to get the velocity, should i just do 21 x (.75)???

2. Nov 13, 2009

### HallsofIvy

Where did you get ".75"?

Any way, if the distance from one crest to another is 21 km, then the length of the wave is 42 km. The time for one end of the wave to "move" to the other is the period, 12 minutes.

3. Nov 13, 2009

### Staff: Mentor

You have posted the same question in another section. That's not a good thing to do, as responders can waste time answering a question that has already been answered.