A stone is dropped from a height of 80 m. Time to reach ground (g=10) is MCQ with Answer and Explanation

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A stone is dropped from a height of 80 m. Time to reach ground (g=10) is

A. 8 s

B. 4 s

C. 2 s

D. 16 s

Answer: Option B

Solution (By JKExamLibrary)

h = ½gt² => 80 = 5t² => t²=16 => t=4 s.

This question belongs to: Science Physics

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B ∝ N. Double turns ⇒ double field at center. Direct proportionality from Biot-Savart law. Memory tip: 'Coil field: B ∝ NI; more turns ⇒ stronger field'. Magnetism formula frequently tested in competitive exams.

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g = 4π²l/T² ⇒ %Δg = %Δl + 2×%ΔT. Assuming l precise: %Δg ≈ 2×(0.1/2.0×100%) = 2×5% = 10%. Memory tip: 'g ∝ 1/T² ⇒ %Δg = 2×%ΔT'. Error analysis frequently tested in competitive experimental physics sections.

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