OnlineOcean 101 - Hints for Lab #1

Some Hints for LAB: Marine Charts and Navigation

Geology 105 - Oceanography

Question #
Hint

Overall

On All Labs:

* Organize and write your answers as clearly and completely as you can. If I don’t understand your answer, I can’t give you credit for it. I’m into “WHY”, so explain your answers well.

* Show all your work. Show each step of calculations, including all units along the way. This helps me give you partial credit.

* You are encouraged to share ideas, but don’t copy or give answers! Everyone must do their own work, write their answers in their own words, and be able to explain them to me.

* Explaining concepts helps you really learn it, so if you think you might be able to address a classmate's question without "giving away" the answer, please do try!

On This Lab:

* Remember that latitude lines run East-West (the equator is 0° latitude, the poles are 90° N & 90° S latitudes). Longitude lines run North-South (0° longitude is in Greenwich, England, and 180° longitude is in the middle of the Pacific Ocean).

* Thus, latitude lines show distances (in degrees!) N & S of the equator, and longitude lines show distances (in degrees!) E & W of Greenwich.

* Remember that 1 degree of latitude or longitude equals 60 minutes ("minutes" in this usage has nothing to do with time). In other words, 1° = 60'. So, for example, 20°30' N is halfway between 20°N and 21°N latitude.

* Do not ignore the minutes of latitude and longitude (that is, do not round off your work to just degrees).

1a - 1f
If you want to know which of two locations is farther north or south, compare their latitudes. If you want to know which is farther east or west, compare their longitudes. Always check which hemisphere each location is in (N, S, E, W).

1g

Refer to the "Units of Distance and Speed" section in the lab background information.

1h - 1i

Refer to the "Time and the Earth's Rotation" section in the lab background information.

2

To show you how to do unit-conversion problems in a nice methodical way that helps minimize math errors, I'll walk you through Question #2 here. We will be doing a lot of unit-conversions in this course, so it's worth learning now. Also see the "Scientific Method & Math Practice" assignment's background information. If you have a better way of explaining this type of question to your classmates -- and/or if you find good math websites -- please do let us know!

“The distance between two points is 80 statute miles. How far is that in nautical miles?”

a) Recognize that this is a unit-conversion problem.

b) What unit conversion factor(s) do you need to answer it? (Always write down the relevant conversion factors and equations at the very beginning of a math problem.)

1 statute mile = 0.87 nautical miles
or (equally valid)
1 nautical mile = 1.15 statute miles
c) 80 statute miles = ?

d) 80 s.m. x __________ = ??? n.m. (If you multiply a value by 1, it doesn't change that value. So, you can put one side of a conversion factor equation in the top of a fraction, and the other side of the equation in the bottom of a fraction, then multiply that fraction by your value that you're trying to convert.)

e) 80 s.m. x _____(n.m./s.m) = ??? n.m. (How do you know which side of the conversion factor goes in the top, and which goes in the bottom of the fraction? Well, fortunately, UNITS cancel out just like numbers do. For instance, 2 divided by 2 = 1. Likewise, feet divided by feet --> Gets rid of "feet" in your equation. In this question, you have s.m. in the TOP of your value you're converting, so the fraction you're multiplying the value by must have s.m. in the BOTTOM (because s.m./s.m. cancels). This leaves n.m. in the top of the fraction, if you do it correctly. I always start by drawing a HORIZONTAL line for the fraction, and next putting the UNITS in above and below the horizontal line, and finally putting the numbers that go with the units into the fraction.)

f) 80 s.m. x (0.87 n.m. / 1 s.m.) = ??? n.m.
or
80 s.m. x (1 n.m. / 1.15 s.m.) = ??? n.m. (Sorry, I haven't figured out a good way to draw horizontal fraction lines here in .html)

g) 80 statute miles = 69.6 n.m. (Finally, as the last step, plug in the numbers and get your answer.)

h) Check that your answer makes sense.

3 - 14

Read the instructions carefully and try these questions on your own. If you have trouble, please ask. Make sure that there's time for me to respond - Ask early! :)

Okay, here are a couple hints:

-- Question #6: Read the magnetic declination and annual variation off of the Puget Sound compass rose; I'm posting a color copy you can zoom in on for easier reading. For help, see the example ("sample compass rose") in Figure 2 of the lab background information.

-- Question #9: See Figure 3 in the lab background material. Also remember that there are 360 degrees in a circle; geographic north is 0 degrees, east = 90, south = 180, west = 270. Be sure to calculate this answer for the present year.

Question #	Hint
Overall	On All Labs: * Organize and write your answers as clearly and completely as you can. If I don’t understand your answer, I can’t give you credit for it. I’m into “WHY”, so explain your answers well. * Show all your work. Show each step of calculations, including all units along the way. This helps me give you partial credit. * You are encouraged to share ideas, but don’t copy or give answers! Everyone must do their own work, write their answers in their own words, and be able to explain them to me. * Explaining concepts helps you really learn it, so if you think you might be able to address a classmate's question without "giving away" the answer, please do try! On This Lab: * Remember that latitude lines run East-West (the equator is 0° latitude, the poles are 90° N & 90° S latitudes). Longitude lines run North-South (0° longitude is in Greenwich, England, and 180° longitude is in the middle of the Pacific Ocean). * Thus, latitude lines show distances (in degrees!) N & S of the equator, and longitude lines show distances (in degrees!) E & W of Greenwich. * Remember that 1 degree of latitude or longitude equals 60 minutes ("minutes" in this usage has nothing to do with time). In other words, 1° = 60'. So, for example, 20°30' N is halfway between 20°N and 21°N latitude. * Do not ignore the minutes of latitude and longitude (that is, do not round off your work to just degrees).
1a - 1f	If you want to know which of two locations is farther north or south, compare their latitudes. If you want to know which is farther east or west, compare their longitudes. Always check which hemisphere each location is in (N, S, E, W).
1g	Refer to the "Units of Distance and Speed" section in the lab background information.
1h - 1i	Refer to the "Time and the Earth's Rotation" section in the lab background information.
2	To show you how to do unit-conversion problems in a nice methodical way that helps minimize math errors, I'll walk you through Question #2 here. We will be doing a lot of unit-conversions in this course, so it's worth learning now. Also see the "Scientific Method & Math Practice" assignment's background information. If you have a better way of explaining this type of question to your classmates -- and/or if you find good math websites -- please do let us know! *“The distance between two points is 80 statute miles. How far is that in nautical miles?”* a) Recognize that this is a unit-conversion problem. b) What unit conversion factor(s) do you need to answer it? (Always write down the relevant conversion factors and equations at the very beginning of a math problem.) 1 statute mile = 0.87 nautical miles or (equally valid) 1 nautical mile = 1.15 statute miles c) 80 statute miles = ? d) 80 s.m. x __________ = ??? n.m. (If you multiply a value by 1, it doesn't change that value. So, you can put one side of a conversion factor equation in the top of a fraction, and the other side of the equation in the bottom of a fraction, then multiply that fraction by your value that you're trying to convert.) e) 80 s.m. x _____(n.m./s.m) = ??? n.m. (How do you know which side of the conversion factor goes in the top, and which goes in the bottom of the fraction? Well, fortunately, UNITS cancel out just like numbers do. For instance, 2 divided by 2 = 1. Likewise, feet divided by feet --> Gets rid of "feet" in your equation. In this question, you have s.m. in the TOP of your value you're converting, so the fraction you're multiplying the value by must have s.m. in the BOTTOM (because s.m./s.m. cancels). This leaves n.m. in the top of the fraction, if you do it correctly. I always start by drawing a HORIZONTAL line for the fraction, and next putting the UNITS in above and below the horizontal line, and finally putting the numbers that go with the units into the fraction.) f) 80 s.m. x (0.87 n.m. / 1 s.m.) = ??? n.m. or 80 s.m. x (1 n.m. / 1.15 s.m.) = ??? n.m. (Sorry, I haven't figured out a good way to draw horizontal fraction lines here in .html) g) 80 statute miles = 69.6 n.m. (Finally, as the last step, plug in the numbers and get your answer.) h) Check that your answer makes sense.
3 - 14	*Read the instructions carefully and try these questions on your own. If you have trouble, please ask. Make sure that there's time for me to respond - Ask early! :)* *Okay, here are a couple hints:* -- Question #6: Read the magnetic declination and annual variation off of the Puget Sound compass rose; I'm posting a color copy you can zoom in on for easier reading. For help, see the example ("sample compass rose") in Figure 2 of the lab background information. -- Question #9: See Figure 3 in the lab background material. Also remember that there are 360 degrees in a circle; geographic north is 0 degrees, east = 90, south = 180, west = 270. Be sure to calculate this answer for the present year.