A body of mass falls freely from rest through a height of . What is its speed on reaching the ground? (take , answer in m/s)

Answer and explanation

Correct answer: B. 20

  1. Step 1: By conservation of mechanical energy, the loss in gravitational potential energy during free fall equals the gain in kinetic energy: .
  2. Step 2: The mass cancels from both sides, showing the impact speed depends solely on height: .
  3. Step 3: Substitute and : .
Answer
20.

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