Calculating Hydraulic Jump with Unknown Cross Sectional Area: Help Needed

AI Thread Summary
The discussion revolves around calculating the hydraulic jump while solving for h2, where the user is confused about the base measurement of the water's cross section. The manual suggests canceling out the bases of the smaller and larger streams, but the user disagrees, arguing that the smaller stream should have a narrower base. This disagreement stems from the lack of provided dimensions for the reservoir channel, complicating the calculation. The user seeks clarification and assistance, specifically requesting a diagram to better understand the problem. The conversation highlights the importance of accurate base measurements in hydraulic calculations.
LT72884
Messages
335
Reaction score
49
Homework Statement
A hydraulic jump (see Video V10.11) is in place downstream
from a spillway as indicated in Fig. P5.10. Upstream of
the jump, the depth of the stream is 0.6 ft and the average stream
velocity is 18 ft/s. Just downstream of the jump, the average stream
velocity is 3.4 ft/s. Calculate the depth of the stream, h, just downstream
of the jump.
Relevant Equations
Q1=Q2 or V1A1=V2A2 where A is the cross sectional area of the water.
I have 90% of this done. When i looked in my manual i noticed an odd jump they made and i don't get why. that is where i need the help

V1(b1h1) = V1(b2h2)

Im solving for h2.

What i can't figure out is what to use for the base measurement of the cross section of the water. i have no idea how wide the reservoir channel is. It never gave me that number and we can't just "assume" that the base is the same in the smaller stream than it is in the larger stream. But the solution manual made that assumption so that the bases cancel out. I disagree with that. Since the stream IS SMALLER, therefore it has a smaller base than the larger stream at the bottom... Canceling out the bases can't work.

thanks for the help:)
 
Physics news on Phys.org
Could you post a diagram?
 

Similar threads

Replies
3
Views
2K
Replies
6
Views
2K
Replies
10
Views
3K
Replies
4
Views
977
Replies
0
Views
2K
Back
Top