Magnitude of the torque exerted by the water on the wheel, per unit mass flow rate of incoming jet, is

Question

Water having a density of 1000 kg/m³, issues from a Nozzle with a velocity of 10 m/s and the jet strikes a bucket mounted on a Pelton wheel. The wheel rotates at 10 rad/s. The mean diameter of the wheel is 1 m. The jet is split into two equal streams by the bucket; such each stream is deflected by 120⁰, as shown in the figure. Friction in the bucket may be neglected. Magnitude of the torque exerted by the water on the wheel, per unit mass flow rate of incoming jet, is         

      (a) 0 (N-m) / (kg/s)

      (b) 1.25 (N-m) / (kg/s)

      (c) 2.5 (N-m) / (kg/s)

      (d) 3.75 (N-m) / (kg/s)