LE2-C5S11T3pg Determining Distance

Purpose The purpose of this lesson is to teach you how to answer questions pertaining to time, rate, and distance so you can successfully navigate to your objective.

1. Convert distances between meters and kilometers, using the metric system of measurement. 2. Determine the straight-line map distance between two points to within 50 meters. 3. Determine the irregular map distance between two points to within 100 meters. 4. Solve time, rate, and distance problems.

CPS Lesson Questions (1-2)

How much do you know about determining distance on a map? A.Quite a bit – I have already learned how to measure distances on topographic maps. B.Some – I have measured distance on road maps. C.None at all – I have not learned how to measure distances yet, but I’m ready to learn.

True or False: There is one technique to determine distance. A.True B.False

Think about the last long road trip you took. List 2-3 techniques you used to determine how far you traveled. (Use CPS “Pick a Student” for this question)

 There are several techniques of determining distance, each involving several considerations or steps.  Errors will ultimately result in missed checkpoints and failure to successfully navigate to your objective.  While all aspects of land navigation deserve particular attention, this is especially true when determining distance.

You should take the following precautions when measuring distance: a) Isolate yourself to avoid being disturbed. b) Put the map on a flat surface. c) Use the most accurate measuring devices available. d) Keep the sharpest point possible on your pencil.

You should take the following precautions when measuring distance: e) Erase tic marks made on the map as soon as they have served their purpose. f) Use a different side of the paper for each new measurement taken. g) Do not trust your memory. h) Take your time. i) Recheck your work.

 In most foreign countries, the metric system of measurement is used.  The two units of measurement you need to be concerned with are the _____ and the ________.  The meter is commonly used to express ground distances. meter kilometer

 If a coordinate scale is used to determine ground distance, ensure it is the same scale on your map.  The straightedge of the lensatic compass is engraved with a graphic scale.

 To determine straight-line distance between two points on a map, lay a straight-edged piece of paper on the map so that the edge of paper touches both points and extends past them.  To convert map distance to ground distance, move the paper down to the appropriate unit of measure on the graphic bar scale.

CPS Lesson Question (3-4)

True or False: Use the same side of the paper for each new measurement taken. A.True B.False

When working in other countries, which two units of measurement do you need to be concerned with? A.Meters B.Kilometers C.Inches D.Both A and B are correct.

 To measure distance along a winding road, stream, or other curved line, you still use the straight edge of a piece of paper.  In order to avoid confusion concerning the starting point, a six-digit coordinate, combined with a description of the topographical feature, should be given for both the starting and ending points.

 In practically every aspect of land navigation, you will ask questions dealing with time, rate, and distance.  Your success will often depend on how accurately you answer questions pertaining to time, rate, and distance.  Time must be expressed in hours.

To convert 15 minutes to a decimal fraction, divide 15 by hours

To determine time required: If you know the average speed (rate) at which you will be moving and how far (distance) you are going, you can find out how long (time) it will take to travel that distance by dividing the distance by the rate.

T = Time D = Distance R = Rate Example: How long will it take to travel 16 ¼ km at a rate of 5 kph? (1) Convert 16 ¼ to a decimal fraction: If ¼ =.25, then 16 ¼ = (2) T = D/R. Divide the Distance (16.25) by the Rate (5).

Example: How long will it take to travel 16 ¼ km at a rate of 5 kph? hours

CPS Lesson Question (5-6)

True or False: Time must be expressed in hours. A.True B.False

How long will it take to travel 20 km at a rate of 5 kph? A.2 hours B.3 hours C.6 hours D.None of the above 4 hours

List the 2-3 ways that the knowledge gained during this lesson can benefit you. (Use CPS “Pick a Student” for this question)

Images in this lesson were taken from:  Microsoft © Clip Art Gallery  Marine Corps Combat Camera