The propeller of a ship can be modelled as a device producing a stream of water of a cylindrical shape, the radius of which is Identical to that of the propeller. For simplicity, the velocity distribution in the stream can be taken uniform.

The propeller is used to propel a ship that is cruising at a speed of 36 km/h. At that cruise speed, the ship experiences a drag force of 1 MN (one Mega Newton)

a) What is the minimum theoretical amount of power (in MW or HP) needed to keep the ship sail at that constant velocity?

b) Determine the stream velocity v (in km/h) needed to supply enough force to balance the drag, if the diameter of the propeller is 2m.

c) Determine the shaft power needed to drive the propeller

d) Are the answers to parts a and c identical? Explain, why they are or are not (This is important)