Boats and Streams: Upstream & Downstream Speedsनाव और धारा: धारा के अनुकूल एवं प्रतिकूल चाल

Master boat and stream mechanics, relative water velocity, round-trip average speeds, and typical UPSC CSAT upstream-downstream word problems.

Overview: Boats and Streams: Upstream & Downstream Speeds अवलोकन: नाव और धारा: धारा के अनुकूल एवं प्रतिकूल चाल

When a boat travels in flowing water (current/stream):
• Let speed of boat in still water = u km/h, and speed of stream = v km/h.
• Downstream (along the current): Stream aids the boat → Effective speed D = u + v.
• Upstream (against the current): Stream opposes the boat → Effective speed U = u - v.
• Speed of boat in still water: u = (D + U) / 2.
• Speed of stream / current: v = (D - U) / 2.
• Average speed for a round trip (equal distance d): Average Speed = (2 * D * U) / (D + U) = (u² - v²) / u.

Essential Formula / Rule:

Downstream Speed (D) = u + v | Upstream Speed (U) = u - v | Boat Speed in Still Water (u) = (D + U)/2 | Stream Speed (v) = (D - U)/2