## Thursday, March 13, 2008

### Trig Assignment team "Jabawakeez"?

So these are the solutions for the question:

Tidal forces are greatest when Earth, the sun, and the moon are in line. When this occurs at the Annapolis Tidal Generating Station, the water has a maximum depth of 9.6 m at 4:30 am and a minimum depth of 0.4m 6.2 hours later.

Here's how our graph looks like. In the question we were given the max and min values of the wave. The max is at 4:30 and we changed the time to its number value by taking the minutes and dividing it by 60 so its new value was 4.5 on the graph. Now it is easier to add 6.2 hours to it, so the min will be at 10.7 on the x axis. With the max and min we can figure out 1/2 of the period. Since the min and max are 6.2 hours apart we use that. 6.2 * 2 = 12.4. But here's the tricky part. If you do 12.4*(1/4) it will not equal 4.5. So we can't do the 1,2,3,4 ticks and automatically write in the values. What we did was 4.5+12.4 to make it easier to graph. The value in the 4th tick on the x axis is now 16.9. The values on the x axis are now 1/4, 1/2, 3/4 of 16.9. Then you'll just put the points on at the max and min. Then we know the patterns of the curve (after the max) will go to the avg value, then min, avg value again, and then the max.

a)Here's an equation in cose. To find D we found the average of the min and max which was 5. We can now find parameter a by subtracting 5 from the max 9.6. B=2pi/period so in our equation it'll be 2pi/12. In our graph here it does not start at the max where cosine starts so it must've moved by 4.5 our parameter c.

b) First we changed 2:46pm to its number value. Since it has passed into night time we can add the 12 hours from the morning. Then all we do is add the 2 hours and 46 minutes. But we divide 46/60 first. So its number value should be 14.7667. We take this value and plug it into t. This can be done on the calculator...and will get an answer of h=7.1641m.

c)In this question we just plugged in 2 into the equation and solved for t.

Benofschool said...

woot we did it!!!

zeph said...

Talking about the first picture, the graph...

shouldn't the arrow of the wave on the left of the x-axis curve up?

Anonymous said...

I don't see anything incorrect. Good job. Although I was pretty confused when you explained the first part. Don't know why, I guess it was just the way it was worded. But nonetheless job well done.

Rence said...

Everything seems to be in order. Just a little suggestion; Add some spaces in your sentences / paragraphs so that it's easier to see and not so cluttered up. Otherwise, it's great :)

.:. J + ME .:. said...

it's jabbawockeez...haha i'm just joshing with you...but yeah i'm definitely kabajabbawockeezmoderning it. haha but yeah everything looks swell...good job.

Skyline said...

Well I just typed my comment but I got an error when I submitted it and it erased everything I said x( Anyways I'll sum it up quick.

1.) The arrow on the left portion of your first graph image is missing (like zeph mentioned.) It should be there.

and 2.) Somewhere in the first paragraph, someone used cose as an abbreviation for cosine. I wouldnt recommend this as it may be mistaken with cosecant. It may have been a typo or just a plain error, but its something to watch out for :)

Anyways good job guys, I vote Correct!

Not Paul said...

After doing a quick read-through of your solution it looks correct, and your method looks good. I haven't checked your numbers but I think your solution is correct :)

m@rk said...

After doing the whole question by myself, I must say that this is the most challenging question among the bunch. It took me about 35 minutes and a lot of coffee. I think that you have the arrow of the wave on the left of the x-axis on the right position contrary to what other people say. Good luck on the upcoming test.

-m@rk

kristina said...

Hey hey! I've just finished looking through it and the only problem that I have with it is that I think your images could've been a bit bigger. It was hard to read some of it, in my opinion. Other than that, I found nothing wrong with it! Good job!

Unknown said...

This confused me.. well, your explainations did really. Maybe you should space it out more or something, I feel like a bunch of information is being thrown at me all at the same time.

But other than that, it looks fine. =)

AnhThi said...

you guys did a good job except it's so hard to read your work... wish you could click the picture to enlarge

Eleven said...

This question looks tough but it seems like you conquered it well. Thus probably creating more things to type and explain. The work is well done and each step is shown. I think you should use more spacing to show what should be seen more important and less important. Overall good job!