Question

1. Two firefighters are fighting a fire with identical water hoses and nozzles, except that one is holding the hose straight so that the water leaves the nozzle in the same direction it comes, while the other holds it backward so that the water makes a U-turn before being discharged. Which firefighter will experience a greater reaction force

Answer 1

The firefighter who holds the hose in the backward direction will experience greater force.

Step-by-step explanation:

Lets take

mass flow rate = m

Inlet velocity = v₁

Exit velocity = v₂

When water leaves in the same direction ,then change in the linear momentum = m (v₂ - v₁)

And we know that change in the linear momentum is known as force.

F₁ =m (v₂ - v₁) ----------1

When water leaves in the opposite direction(U turn) ,then change in the linear momentum = m (v₂ +v₁)

F₂= m (v₂ +v₁) --------2

F₂ >F₁

There fore when water leaves in the U turn pipe will feel more force.

The firefighter who holds the hose in the backward direction will experience greater force.