Solving For Mass Flow Rate of Two Water Jets

[zewei1988]

Homework Statement

I am supposed to find the mass flow rate for the two resulting water jets.

Homework Equations

Bernoulli's equation
Mass Continuity equation
Momentum equation

The Attempt at a Solution

I've assumed the two areas for jet A and B to be equal, and used mass continuity equation to form:

Q = A( va + vb)

and used momentum equation to form

0 = -Qava + Qbvb - Qv

But I have 3 unknowns (A, va, and vb) but only 2 equations, so I'm stuck. Can anyone help me?

 

[tiny-tim]

hi zewei1988!

i don't understand what your va and vb are …

there's no pipes there, it's just the jet spreading out all over the plate

anyway, since the plate's weight is vertical, and is being balanced, shouldn't you start by finding the vertical component of the https://www.physicsforums.com/library.php?do=view_item&itemid=53" of the jet?

 

[zewei1988]

Sorry. my Qa and va are volume flow rate and velocity in jet A, Qb and vb are volume flow rate and velocity in jet B.

I've already solved part (i) of the question. Since the velocity of water jet in A and B are horizontal in direction, i felt there was no need to consider the weight in solving for mass flow rate in A and B.