A car accelerates from rest at 4 m/s² for 5 s, then moves at constant velocity for 5 s. Total distance is MCQ with Answer and Explanation
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Question #1
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Which of the following scientists formulated the 'Uncertainty Principle', stating that exact position and momentum of an electron cannot be simultaneously known?
Correct Answer: Option D
Explanation:
Werner Heisenberg, a German theoretical physicist, published his famous Uncertainty Principle in 1927. The principle dictates a fundamental limit to precision at the quantum level: the more precisely the position of a particle (like an electron) is determined, the less precisely its momentum can be known, and vice versa. Mathematically, delta_x * delta_p >= h/(4pi).
Werner Heisenberg, a German theoretical physicist, published his famous Uncertainty Principle in 1927. The principle dictates a fundamental limit to precision at the quantum level: the more precisely the position of a particle (like an electron) is determined, the less precisely its momentum can be known, and vice versa. Mathematically, delta_x * delta_p >= h/(4pi).
Question #2
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The radius of the nth Bohr orbit in hydrogen atom is proportional to:
Correct Answer: Option C
Explanation:
Bohr model: radius r_n = (4πε₀ħ²n²)/(m_e e²) = n² a₀, where a₀ is Bohr radius (≈0.529 Å). Thus r_n ∝ n². Energy E_n ∝ -1/n². Memory tip: 'Bohr radius: r ∝ n²; energy: E ∝ -1/n²'. This atomic physics formula is frequently tested in competitive exams. Always recall that n is principal quantum number; higher n means larger orbit, less tightly bound electron. This problem assesses understanding of quantization in early quantum theory.
Bohr model: radius r_n = (4πε₀ħ²n²)/(m_e e²) = n² a₀, where a₀ is Bohr radius (≈0.529 Å). Thus r_n ∝ n². Energy E_n ∝ -1/n². Memory tip: 'Bohr radius: r ∝ n²; energy: E ∝ -1/n²'. This atomic physics formula is frequently tested in competitive exams. Always recall that n is principal quantum number; higher n means larger orbit, less tightly bound electron. This problem assesses understanding of quantization in early quantum theory.
Question #3
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In which of the following scenarios is the work done physically zero?
Correct Answer: Option D
Explanation:
Work (W) = F × d × cos(θ). In scenario A, displacement (d) is zero. In scenario B, the applied force (upward) is perpendicular to the displacement (horizontal), so cos(90°) = 0. In scenario C, the centripetal force (gravity) is perpendicular to the satellite's instantaneous direction of motion, so work done is zero. All cases yield zero work.
Work (W) = F × d × cos(θ). In scenario A, displacement (d) is zero. In scenario B, the applied force (upward) is perpendicular to the displacement (horizontal), so cos(90°) = 0. In scenario C, the centripetal force (gravity) is perpendicular to the satellite's instantaneous direction of motion, so work done is zero. All cases yield zero work.
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