A stone tied to the end of string of 80 cm long, is whirled in a horizontal circle with a constant speed. If the stone makes 25 revolutions in 14 s. Then magnitude of acceleration of the same will be

If angular velocity is ω and radius of circular path is r then, acceleration α = ω2rwhere ω = 2πTT = Number of revolutionsTime taken = 2514 = 1.78 sand ω = 2π1.78 = 3.52 rad/sHence, α = (3.52)2×80 = 991.23 = 990 cm/s2