A spring with k=200 N/m is compressed by 0.1 m. Potential energy stored is MCQ with Answer and Explanation

Explanation:
Assertion true: a = -ω²x, max at max |x|. Reason true: F = -kx (Hooke's law), and F = ma ⇒ a ∝ -x. Reason correctly explains why acceleration peaks at extremes. Memory tip: 'SHM: F ∝ -x ⇒ a ∝ -x'. Assertion-reason testing SHM fundamentals, frequently examined in competitive exams.

Explanation:
0.5 kW × 2 h = 1 kWh.

Explanation:
Newton's law of gravitation: F ∝ 1/r². If distance r becomes r/2, new force F' ∝ 1/(r/2)² = 4/r² = 4F. So force quadruples. This inverse square law is fundamental for gravitational, electric, magnetic forces.