A fluid flows into the atmosphere through a circular nozzle and collides with a plate, as shown in the figure.

shown in the figure. A force of $100$N is applied to keep the plate stationary. Calculate:

a$)$ The flow velocity in the largest and smallest sections of the nozzle;

b$)$ The gradient of the mercury column shown in the figure.

Data: specific mass of water is $1000$ kg$/$m$3$

and the specific mass of mercury is $13600$kg$/$m$3$