Since the block starts executing simple harmonic motion from extreme position, we have x = acosωt At 1 s, we have x = 0.2cos(3π) = 0.1 m That is, the block is at a distance 5.1 – 0.10 = 5 m from O, which is the range of the bebble as well. Now, R = gv2sin2α S = 10v2sin2(4π) Therefore, v = 50 m/s.