69. The swing of a spinning cricket ball in air can be explained on the basis of A.Sudden change in wind direction. B.Buoyancy of air. C.Turbulence caused by wind. D.Bernoulli's theorem.
Option C Solution: The main theory of swing bowling surrounded turbulent and laminar airflow. Laminar air separates from the surface of the ball earlier than turbulent flow air, so that the separation point moves toward the front of the ball on the laminar side. On the turbulent flow side it remains towards the back; inducing a greater lift force on the turbulent airflow side of the ball. The calculated net lift force is not enough to account for the amount of swing observed: Additional force is provided by the pressure-gradient force.
