Which of the following physical quantities does NOT have the same dimensions as the other three? MCQ with Answer and Explanation
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Question #1
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A conductor has resistance 4 Ω at 0°C and temperature coefficient α. At what temperature will resistance be 6 Ω? (α=0.004 /°C)
Question #2
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Which of the following scenarios best illustrates conservation of momentum?
Correct Answer: Option C
Explanation:
Conservation of momentum applies to isolated systems with no external forces. In billiard ball collision on frictionless table, external forces (gravity, normal) cancel vertically, and no horizontal external forces act, so horizontal momentum is conserved. Book on table has zero momentum but no dynamic process. Falling ball has external gravity force. Accelerating car has external engine force. Thus only option B represents an isolated system where momentum conservation holds. Memory aid: Momentum conserved when net external force = 0. This conceptual question tests understanding of system boundaries and force analysis, crucial for mechanics sections in competitive exams.
Conservation of momentum applies to isolated systems with no external forces. In billiard ball collision on frictionless table, external forces (gravity, normal) cancel vertically, and no horizontal external forces act, so horizontal momentum is conserved. Book on table has zero momentum but no dynamic process. Falling ball has external gravity force. Accelerating car has external engine force. Thus only option B represents an isolated system where momentum conservation holds. Memory aid: Momentum conserved when net external force = 0. This conceptual question tests understanding of system boundaries and force analysis, crucial for mechanics sections in competitive exams.
Question #3
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Geostationary satellite period:
Correct Answer: Option A
Explanation:
Geostationary: orbit period = Earth's rotation period (24 h), equatorial plane, appears fixed. Orbital radius ≈ 42,000 km from Earth center. Memory tip: 'Geostationary: T=24h, equatorial, fixed position; communication satellites'. Orbital mechanics fact frequently tested in competitive exams.
Geostationary: orbit period = Earth's rotation period (24 h), equatorial plane, appears fixed. Orbital radius ≈ 42,000 km from Earth center. Memory tip: 'Geostationary: T=24h, equatorial, fixed position; communication satellites'. Orbital mechanics fact frequently tested in competitive exams.
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