Note the pronunciation: 劲 is read jìng (fourth tone) when meaning "strong, powerful" in literary compounds (劲风, 劲敌, 劲旅), but read jìn (fourth tone, different initial) when meaning "strength, energy" in colloquial usage (有劲, 没劲).
mistakes
Don't confuse 劲风 (jìngfēng, strong wind) with 净风 or 静风 — 劲 here carries the sense of forceful, unyielding, and is the same character used in 劲敌 (formidable rival).
