一題大一普物英文題

Question

[Question]

The navigator of an oil tanker uses the satellites of the Global Positioning System (GPS/NAVSTAR) to find latitude and longitude .
These are 43度36分25.3秒N and 77度31分48.2秒W.
If the accuracy of these determination is ±0.5秒 , what is the uncertainty in the tanker's position measured along (a) a north-south line  (merdian of longitude) and (b) an east-west line (parallel of latitude)? (c) Where is the tanker?

[Answer]

(a)31m
(b)22m

可以請教過程嗎?還有紅色字體意思是怎麼?
拜託了~~

pauillac 17 · Accepted Answer

what is the uncertainty in the tanker's position measured along (a) a north-south line
uncertainty在此是不確定量的意思, 南北線就是經度, 東西線是緯度 
油輪的導航員用GPS量得的經緯度有多少不確定量?

既然準確度是±0.5秒, 不確定量就是角度1秒, 將那個地點的子午線每度的長度乘以1秒就是不確定量的長度

那個地點的經度線每度的長度是111公里, 緯度線每度的長度是80公里, 1度是3600秒, 除一除,便是31m和22m

經度線長幾乎是constant, 緯度線長則與緯度關係甚大
http://en.wikipedia.org/wiki/Longitude
 Latitude  N-S radius
of curvature

圖片參考：http://upload.wikimedia.org/math/0/1/f/01ff7f895fd77d6be1da38f3e913d8ac.png
  Surface distance
per 1° change
in latitude   E-W radius
of curvature

圖片參考：http://upload.wikimedia.org/math/6/3/1/631fe013c550a2dc153c1017cd15c438.png
  Surface distance
per 1° change
in longitude 0°6335.44 km110.574 km6378.14 km111.320 km15°6339.70 km110.649 km6379.57 km107.551 km30°6351.38 km110.852 km6383.48 km96.486 km45°6367.38 km111.132 km6388.84 km78.847 km60°6383.45 km111.412 km6394.21 km55.800 km75°6395.26 km111.618 km6398.15 km28.902 km90°6399.59 km111.694 km6399.59 km0.000 km

一題大一普物英文題

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