The force exerted on the wall by a water jet can be determined using the principles of fluid dynamics and Newton's laws of motion. Let's break down the problem into several key steps:

Step 1: Determine the momentum change of the water jet
The momentum change of an object can be calculated using the equation:
Δp = m * Δv,
where Δp is the change in momentum, m is the mass, and Δv is the change in velocity.

In this case, the mass of the water jet can be determined using the equation:
m = ρ * A * Δx,
where ρ is the density of water, A is the cross-sectional area of the jet, and Δx is the distance the jet travels before rebounding.

Step 2: Calculate the velocity change of the water jet
The velocity change of the water jet can be determined by considering the angle of incidence (θ) and the velocity of the jet (v). The component of velocity perpendicular to the wall is given by:
v_perpendicular = v * cos(θ),
and the component of velocity parallel to the wall is given by:
v_parallel = v * sin(θ).

Since the water jet rebounds elastically, the change in velocity perpendicular to the wall is equal in magnitude but opposite in direction:
Δv_perpendicular = -2 * v_perpendicular.

The change in velocity parallel to the wall remains zero since the water jet does not bounce back in that direction:
Δv_parallel = 0.

Step 3: Calculate the force exerted on the wall
The force exerted on the wall can be determined using Newton's second law of motion:
F = Δp / Δt,
where F is the force, Δp is the change in momentum, and Δt is the time taken for the momentum change.

Since the velocity change is instantaneous in an elastic collision, the time taken for the momentum change is very small.

Step 4: Simplify the equation
Combining the equations from steps 1, 2, and 3, we have:
F = m * Δv_perpendicular / Δt.

Substituting the values, we get:
F = ρ * A * Δx * (-2 * v_perpendicular) / Δt.

Step 5: Evaluate the equation
To evaluate the equation, we need to consider the specific values of density, cross-sectional area, distance traveled, velocity, and time taken. By plugging in these values, we can calculate the force exerted on the wall.

Remember to double-check your units and ensure they are consistent throughout the calculations.

In conclusion, the force exerted on the wall by a water jet rebounding elastically can be calculated by determining the momentum change of the jet and dividing it by the time taken for the change. By following the steps outlined above, you can calculate the force exerted on the wall in a detailed and systematic manner.