Which of the following is a renewable source of energy? MCQ with Answer and Explanation

Explanation:
Hygrometer measures relative humidity. Wet and dry bulb, hair hygrometer. Hydrometer measures liquid density. Anemometer wind speed. Barometer pressure.

Explanation:
During phase change (melting), heat energy (latent heat) is used to overcome intermolecular forces, increasing potential energy while kinetic energy (hence temperature) remains constant. Temperature reflects average kinetic energy; since it doesn't change, kinetic energy is unchanged. The energy breaks hydrogen bonds in ice, allowing molecules to move freely in liquid. Memory tip: 'Latent heat changes state, not temperature'. This conceptual question tests understanding of microscopic interpretation of phase changes, frequently examined in competitive tests to assess depth beyond formula recall.

Explanation:
Gravity acts vertically; horizontal displacement ⇒ angle = 90° ⇒ W = Fd cos90° = 0. No work for perpendicular force-displacement. Memory aid: 'Work = Fd cosθ; θ=90° ⇒ W=0'. Mechanics concept frequently tested to correct misconception that force always does work.