The thrust, T, delivered by a ship's propeller is proportional to the square of the propeller rotation speed, R, times the fourth power of the propeller diameter, D.
a) What happens to the thrust if the propeller speed is doubled?
b) What happens to the thrust if the propeller diameter is doubled?
c) If the propeller diameter is increased by 50%, by how much can the propeller speed be reduced to deliver the same thrust?
I have found out the equation to this to be "T = k*R^2*D^4.
I think I found out how to do a) and b). Since they are proportional I can just set it to T = R^2 and T = D^4 and then plug in 2 for R and D. The answer should be 4 and 16 times greater.
I still need help with c) What would we need to do to find how much the propeller speed be reduced to deliver the same thrust?