Practice question

Given: A stone is thrown upwards with a speed of 18 m/s . What is its velocity after 2 s ? (Take g = 10 m/s² ) These values define the system as per NCERT data. Formula: Use v = v_0 + a t. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Here, v_0 = 18 m/s, a = -10 m/s², t = 2 s . Substitute: v = 18 - 10 · 2 = 18 - 20 = -2 m/s . The velocity is -2 m/s (downward). 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.