In my JLPT workbook, it gives these examples to explain the difference between 延{の}びる and 伸{の}びる:
髪{かみ}は[1]{いっ}か[月]{げつ}に1センチぐらい伸{の}びる。
会議{かいぎ}はいつも30分{ぷん}ぐらい延{の}びる。
They both mean "stretch", more or less, so I assumed the difference was that 延{の}びる was more about time and space, and 伸{の}びる is more about distance and length.
However, take a look at this practise question:
1972年、東京{とうきょう}から大阪{おおさか}までだった東海道{とうかいどう}新幹線{しんかんせん}は岡山{おかやま}まで____________。
A 長引{ながひ}いた B 広{ひろ}がった C 延{の}びた D 伸{の}びた
I chose, D, because it was about length.
According to the book, though, the answer is C.
How can I make sense of this answer in light of the example sentences?
のびるwhich can have both伸びるand延びる.伸びるis almost for physical stuff and the other is for space and time. An exception I know is[金]{きん}を[叩]{たた}いて[延]{の}ばす, which meansBeat out gold. Also: http://dictionary.goo.ne.jp/jn/172188/meaning/m0u/ – puhitaku Nov 29 '15 at 06:51