1For a round object or thing to move by rotating along the ground or a slope.
サッカーボールが道路まで転がっていった。
The soccer ball rolled all the way out into the street.
棚から缶詰が落ちて床を転がった。
A can fell off the shelf and rolled across the floor.
坂道で自転車のタイヤが外れて転がっていった。
The bicycle's tire came off and rolled away down the slope.
丸太が斜面を転がり落ちた。
The log tumbled down the slope.
2For a person or object to lose balance and fall over, or flip over.
氷の上で足を滑らせて転がってしまった。
I slipped on the ice and fell over.
突風で自転車が転がって壊れた。
A gust of wind knocked over the bicycle and it broke.
柔道の受け身を習うと、うまく転がって衝撃を減らせる。
If you learn judo breakfalls, you can roll well to reduce the impact.
3To sprawl out and lie down casually, e.g. flopping onto a sofa or the floor; a colloquial expression.
休日は一日中ベッドに転がって過ごした。
On my day off, I spent the whole day just lying around in bed.
疲れた彼は玄関に着くなり床に転がった。
As soon as he got to the front door, exhausted, he flopped down on the floor.
4To describe things lying scattered around or left in place; commonly used as '~が転がっている'.
彼の部屋にはいつも脱いだ服が転がっている。
His room always has clothes he's taken off lying all around.
工事現場には鉄パイプがあちこちに転がっていた。
At the construction site, steel pipes were lying scattered all over.
5For the course of events or a situation to change or unfold in a certain direction, as in 'the discussion rolled along nicely.'
交渉は思わぬ方向に転がっていった。
The negotiations rolled in an unexpected direction.
事態がここまで大きく転がるとは誰も予想していなかった。
No one expected the situation to snowball this far.
6For something (an object, an opportunity) to be readily available or common, coming easily without effort; often used in the negative, e.g. 'opportunities like that don't just lie around.'
そんなおいしい話はそう簡単には転がっていない。
A deal that good doesn't just fall into your lap so easily.
無料でもらえるものが転がっているわけではない。
Free stuff doesn't just come easily or lie around waiting for you.