Practice question

Given: A 0.31 kg stone is whirled in a horizontal circle of radius 1.3 m at 54 rev/min . What is the tension? (Take g = 10 m/s² ) These values define the system as per NCERT data. Formula: Angular speed: omega = 54 × 2π/60 = 9π/5 rad/s. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: omega² = (9π/5)² = 81π²/25 approx 31.99 . Tension: T = m omega² r = 0.31 × 31.99 × 1.3 . T approx 0.31 × 31.99 × 1.3 approx 12.9 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.