A force of 10 N acts on a body of mass 2 kg initially at rest. The momentum acquired by the body after 5 seconds is: MCQ with Answer and Explanation

Explanation:
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:
v ∝ 1/√r. If r' = 2r, v' = v/√2. Orbital velocity decreases with increasing radius. Memory aid: 'Higher orbit ⇒ slower speed; v ∝ r⁻¹/²'. Proportional reasoning question testing gravitation formula application, frequently appearing in competitive exams without heavy calculation.

Explanation:
A micrometer screw gauge uses the principle of a screw rotating in a nut to measure very tiny dimensions (like the diameter of a thin wire). It features a linear main scale and a rotating circular scale on the thimble. While a Vernier caliper measures small distances using sliding scales, the screw gauge generally offers greater precision (least count often 0.01 mm or 0.001 mm).