Practice question

Given: A 35 g bullet at 1200 m/s emerges from a block with 80% of its initial kinetic energy. What is its emergent speed? These values define the system as per NCERT data. Formula: Initial K = 1/2 × 0.035 × 1200² = 25200 J. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Final K = 0.8 × 25200 = 20160 J . 1/2 × 0.035 × v_f² = 20160 Rightarrow v_f² = 1152000 Rightarrow v_f = sqrt1152000 approx 1073.3 m/s . 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.