Answer
see solution
Work Step by Step
(a) The water that is in the hose exerts a force on the water that is about to a result, this water also exerts a reaction force to the hose which exit the nozzle, which causes the water to exit the nozzle at high speed. As exerts a large backward force on the firefighter.
(b) If another firefighter steps on the hose, forming a constriction, the speed of water will increase in the hose due to the reduction in the area as
Flow per unit time = Area * Velocity
If the increase in speed is sufficiently large, turbulent flow takes place which is unsteady and chaotic. This is the reason why the hose begins to pulsate wildly
