A boy of mass 30 kg jumps off a low wall with negligible initial velocity. After 1 second of free fall, his velocity is approximately (g = 10 m/s²):

In free fall, acceleration = g = 10 m/s² downward. Starting from rest (u = 0), after t = 1 s: v = u + gt = 0 + 10 × 1 = 10 m/s downward. *Note: the answer doesn't depend on the boy's mass — all bodies in free fall accelerate at the same rate.*