NDA · 2023 Science & Technology › Physics & ChemistryA railway wagon (open at the top) of mass M1 is moving with speed v1 along a straight track. As a result of rain, after some time it gets partially filled with water so that the mass of the wagon becomes M2 and speed becomes v2. Taking the rain to be falling vertically and water stationary inside the wagon, the relation between the two speeds v1 and v2 is :
🔎 The pattern behind this question
This is the same idea UPSC keeps returning to. Start a free trial to see the answer and the full map.
Across examsNDA 1 · CISF 1
Evolution“Conservation of Momentum” tested across 2 years (2023–2026)
Study how UPSC repeats — not just the papers
₹199 / 1 year · Founding Member
Full access unlocks the three things no PYQ PDF gives you:
① Cross-exam learning — see the same idea recur across CSE, CAPF, CDS and NDA.
② Topic evolution — how each idea is framed, year by year.
③ Question intelligence — every PYQ + answer, linked to related concepts and similar questions.
e.g. Round Table Conference: CDS 2017 → CSE 2017 → … → CAPF 2024
15 days free, no card required — then ₹199 for 1 year.
Start your 15-day free trial →