can you help me with this problem??????

Question

i have been asking so many questions but i still dont understand. how the heck can you determine how far a city is from the equator and prime meridian? its easy to just go on the web and find out but i want to know how you calculate it. can somebody Please give me an math explanation?????? of how to find out how far a city is from the equator and meridian?

Answer 1

Start with the Latitude and Longitude of the city. This tells you how north (or south) of the equator you are and how east (or west) of the prime meridian you are. To calculate how far, you just need to know the radius of the earth. Assuming the earth is approximately a sphere, then radius is about Re=6378.1 km, then the distance along the earth can be found by the arclength of the sector swept out by the angles of latitude and longitude.

I find about 60 nautical miles per degree of latitude or longitude. (assuming spherical earth)
Distance from equator ~ Re*Lat*pi/180
Distance from PM ~ Re*Long*pi/180

you have to use the pi/180 (pi ~3.14156...) to convert from degrees to radians (since the angle must be in radians for this to work). If the answer comes out negative that just meas you are either south of the equator or west of the PM.

Answer 2

A very good quesrion indeed.The easiest part is to determine the latitude ( by measuring the angular height of the sun , eg): How far north or south , in angle, you are from the equator. Equator is a natural divider between north and south. There is no such thing for east/west. Zero meridian is an arbitrary reference. Instead of Greenwich you could have had it through Paris.(The currency of the term Middle-East tells you that the geo-political reference meridian now passes through US)


Through lat and long you know where you are on the earth. To convert these angles into dist is a tough task. You first physically measure a long meridianal arc. Then you construct a mathemmatical model of the earth( search for Everest geoid, eg).This gives you an equation telling you that one degree equals so many km.

Answer 3

Here's a two-step procedure you can try:

1. Determining the distance from the equator is the easy part. Since lines of latitude are all parallel to the equator, simply find the number of degrees and fraction of a degree the city lies from the equator. One degree of latitude equals 111.1 kilometers.

2. Since lines of longitude converge at the poles, the distance between each degree changes consistently as they get narrower the closer they come to the poles. A simple mathmatical correction is required. In this case, use the degree of latitude you found in Step 1 and multiply it by its cosine. This gives you the necessary correction factor to compute the distance between degrees at a given longitude.

For this problem you can disregard the minus signs for West longitude and South latitude since you are just interested in the distances.

Example: Melbourne, Australia is located at roughly 37.8° South latitude, 145° East longitude.

1. 37.8° X 111.1kilometers = 4,199.6 km South of the Equator.

2. Compute the correction factor. Cosine 37.8° = 0.79. Find the distance from the Prime Meridian. 111.1km X 0.79 = 87.8 km. 145° X 87.8 km = 12,731 km from the Prime Meridian.

If you need the distances in a different measurement (statute miles or nautical miles) just apply the appropriate conversion factors. By the way, all the above computations are based on the standard definition of the distance of one minute of latitude = 1.852 km which is also the definition of one nautical mile. I hope this helps.

Answer 4

latitude and longitude.
the earth is divided into a particular number of lines...both horizontally and vertically. the distance b/w each line is fixed.
equator is the starting point horizontally and primes meridian is the starting point vertically. you count the number of lines between the required place and equator/ p.meridian and you get a point...which is the place you are locating. distance is calculated by multiplying number of lines by the distance between two lines.
(just like you plot points on a graph sheet taking x axis and y axis....in the same way you locate a point on the earth's grid by taking equator and prime meridian as reference points.

Answer 5

AKA latitude and longitude = easy to look up. 1 Nautical mile is 1/100 th of a degree if memory serves.

Answer 6

70mi=1degree Longitude
cosine of Degree Latitude * 70mi = Miles for latitude

Because as you move north or south away from the equator the lines of latitude actually get shorter in distance proportionally as you move closer to the poles.

Check out this website to explain : http://mathforum.org/library/drmath/view/55461.html

Answer 7

See http://cas.umkc.edu/geo/env-sci/module1/weblab1.htm. It has everything about positioning yourself in a global grid reference system.