Which combination of the following statements about steady incompressible forced vortex flow is correct ?P. Shear stress is zero at all points in the flow.Q. Vorticity is zero at all points in the flow.R. Velocity is directly proportional to the radius from the centre of the vortex.S. Total mechanical energy per unit mass is constant in in the entire flow.

Which combination of the following statements about steady incompressi

1.	Which combination of the following statements about steady incompressible forced vortex flow is correct ?P. Shear stress is zero at all points in the flow.Q. Vorticity is zero at all points in the flow.R. Velocity is directly proportional to the radius from the centre of the vortex.S. Total mechanical energy per unit mass is constant in in the entire flow.
A.	P and Q
B.	R and S
C.	P and R
D.	P and S
Answer» D. P and S