Nuclear fission is the splitting of a heavy nucleus (e.g., uranium-235, plutonium-239) into lighter nuclei, releasing energy and neutrons. This process powers nuclear reactors and atomic bombs. Fusion combines light nuclei (e.g., hydrogen to helium), powering stars. Memory aid: 'Fission = splitting heavy; Fusion = joining light'. This conceptual question tests understanding of nuclear reactions, frequently examined in competitive exams. Always link fission to chain reactions (neutrons induce further fissions) and critical mass concepts.
Explanation:
In SHM, a = -ω²x, acceleration ∝ -displacement. Minus sign indicates direction towards mean position (restoring). Characteristic of SHM. Pendulum and spring-mass system exhibit SHM for small displacements.
Explanation:
Average speed = Total distance / Total time. Let distance AB = d km. Time for AB = d/40 h, time for BA = d/60 h. Total distance = 2d km. Total time = d/40 + d/60 = d(3+2)/120 = 5d/120 = d/24 h. Average speed = 2d / (d/24) = 48 km/h. Note: Average speed is not arithmetic mean of speeds (which would be 50 km/h) because time intervals differ. This harmonic mean concept is crucial for motion problems. Exam tip: For equal distances, average speed = 2v₁v₂/(v₁+v₂). Frequently tested in competitive exams.
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