Practice question

Given: A 40 kg man in a lift accelerating downward at 3 m/s² stands on a scale. What is the reading? (Take g = 10 m/s² ) These values define the system as per NCERT data. Formula: Net force: N - mg = ma, where a = -3 m/s². This is the standard NCERT relation for this phenomenon. Substitution & Calculation: The scale shows the normal force. . N - 40 × 10 = 40 × (-3) . N - 400 = -120 Rightarrow N = 280 N . Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻¹ K⁻¹, m/s², 10⁻⁵ are properly used as per NCERT.