Practice question

Given: A train moving at 36 km/h accelerates at 0.5 m/s² for 20 s, then decelerates at 1 m/s² to rest. What is the total distance covered? These values define the system as per NCERT data. Formula: Initial speed: 36 km/h = 10 m/s. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Phase 1: v = 10 + 0.5 · 20 = 20 m/s, x_1 = 10 · 20 + 1/2 · 0.5 · (20)² = 200 + 100 = 300 m . Phase 2: t = 20/1 = 20 s, x_2 = 20 · 20 - 1/2 · 1 · (20)² = 400 - 200 = 200 m . Total = 300 + 200 = 500 m . 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.