How Do You Calculate Force on a Water Jet Deflected by a Plate?

[michael7777]

Homework Statement

A jet of water going through a nozzle is deflected by a flat plate. Get Q, Velocity, Force

The volumetric flow rate of water through the nozzle is 10 Litres in 7 seconds

The water temperature is 20 degrees celcius.
We are using a flat plate so theta = 90 degrees
Velocity coefficient C = 1

Homework Equations

Q (volume flow rate) = volume / time
Velocity = Q / area of nozzle
Force = density of water * Area of nozzle * velocity^2 * (1 - C*cos theta)

The Attempt at a Solution

Density of water at 20 degrees = 998.2 kg/m^3
Q = 0.01 / 7
Q = 1.429 (10^3) m^3/s

I don't know how to get area of nozzle

Using C = 1, theta = 90:
F = 1000 * area of nozzle * V^2

 

[tiny-tim]

A jet of water going through a nozzle is deflected by a flat plate. Get Q, Velocity, Force

The volumetric flow rate of water through the nozzle is 10 Litres in 7 seconds
…
I don't know how to get area of nozzle

Hi michael7777!

I agree with you … there isn't enough information.

(btw, another way of calculating it is force = rate of change of momentum = mass x velocity/time … but again, we don't know the velocity. )