Which of the following graphs represents a body at rest? MCQ with Answer and Explanation

Explanation:
Loudness correlates with intensity, which is proportional to square of amplitude. Frequency determines pitch. Larger amplitude → louder sound. Measured in decibels.

Explanation:
Galileo Galilei conducted experiments rolling balls down inclined planes and concluded that an object in motion would continue moving indefinitely on a frictionless surface. This completely challenged Aristotelian mechanics and formulated the concept of inertia, which Isaac Newton later formalized as his First Law of Motion.

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.