Newton's First Law of Motion is also known as the Law of: MCQ with Answer and Explanation

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).

Explanation:
Above 20 kHz.

Explanation:
Beats occur due to interference of two waves with slightly different frequencies (Δf small, typically < 10 Hz for audible beats). The beat frequency is |f₁ - f₂|, causing periodic loudness variation. Same frequency (A, B) produces steady interference (no beats); very different frequencies (D) produce rapid fluctuations not perceived as beats. Memory aid: 'Beats: |f₁ - f₂| small ⇒ audible pulsations; used in tuning'. This wave phenomenon question tests superposition understanding, frequently examined in competitive exams. Always link beat perception to frequency difference magnitude; competitive exams often test qualitative conditions for observable beats.