One astronomical unit (AU) is the MCQ with Answer and Explanation

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.

Explanation:
Binding energy per nucleon peaks around iron-56 (≈8.8 MeV/nucleon), making it the most stable nucleus. Lighter nuclei release energy via fusion; heavier via fission. Hydrogen has near-zero binding energy per nucleon; uranium ≈7.6 MeV/nucleon. Memory aid: 'Iron peak: most stable nucleus; fusion before, fission after'. This nuclear physics concept is frequently tested in competitive exams. Always link binding energy curve to energy release in stars (fusion) and reactors (fission).

Explanation:
Ammeter must be in series to measure full current. Very low internal resistance.