Assuming ideal flow, the force F in newtons required on the plunger to push out the water is

Question

Statement for Linked Answer Q01 & Q02

A syringe with a frictionless plunger contains water and has at its end a 100 mm long needle of 1 mm diameter. The internal diameter of the syringe is 10 mm. Water density is 1000 kg/m³. The plunger is pushed in at 10 mm/s and the water comes out as a jet.         

1. Assuming ideal flow, the force F in newtons required on the plunger to push out the water is

      (a) 0                                                                    (b) 0.04

      (c) 0.13                                                               (d) 1.15

 

 2. Neglect losses in the cylinder and assume fully developed laminar viscous flow throughout the needle; the Darcy friction factor is 64/R_e, Where R_e is the Reynolds number. Given that the viscosity of water is 1.0´10^–3 kg/m s, the force F in Newton required on the plunger is

      (a) 0.13                                                               (b) 0.16

      (c) 0.3                                                                 (d) 4.4