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⚛️ Physics  ·  Work, Energy and Power  ·  NEET & JEE

Two bodies of masses 1 kg and 4 kg have equal kinetic energies. The ratio of their momenta (lighter : heavier) is:

Answer: 1:2.

  • A 1:1
  • B 2:1
  • C 1:4
  • D 1:2

Correct answer: D. 1:2

Explanation: Since p = √(2mKE) and KE is equal, p ∝ √m. So the ratio is √1 : √4 = 1:2.

Energy Conservation: KE ⇄ PE on a SwingA: PE maxKE = 0B: KE maxPE minC: PE maxKE = 0

As a pendulum swings, total mechanical energy (KE+PE) stays constant: at the highest points A and C, all energy is potential (zero speed); at the lowest point B, all of that energy has converted into kinetic energy (maximum speed).

Concept context

Work-energy theorem, potential energy, conservation of energy, collisions.

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