How Do You Calculate the Holding Force of a Water Nozzle?

AI Thread Summary
To calculate the holding force of a water nozzle with a radius of 25mm and a flow rate of 750L/min, the fluid velocity is determined to be approximately 6.366 m/s. The challenge lies in calculating the pressure needed to derive the force, which is ultimately given as 79N, corresponding to a pressure of about 40,000 pascals. The discussion highlights the use of various fluid dynamics equations, including the impulse-momentum equation, to solve for the required force. Despite initial difficulties with variable management in the equations, clarity is achieved through community input. Understanding these principles is crucial for accurately calculating the holding force of a water nozzle.
techninja
Messages
14
Reaction score
0

Homework Statement


A nozzle has a radius of 25mm. Water emerges at the rate of 750L/min. Find the force with which the nozzle must be held.

Homework Equations


F = m \times a
\Delta m / \Delta t = pAv
A_1 \times v_1 = A_2 \times v_2
R = vA

The Attempt at a Solution


I've so far been able to calculate fluid velocity: v = r/A = 6.366m/s. However, finding pressure in order to find force eludes me. I've tried looking into different units, trying the above formulae (but there's always one variable somehow dangling somewhere), and so on.

The answer is given to be 79N, so I do know that pressure is equal to about 40000 pascals. This, of course, doesn't help much.

Any help is very much appreciated. :redface:
 
Physics news on Phys.org
Try looking at a variation of the impulse-momentum equation, Ft = m delta v
 
Thank you verily much for your input. I completely understand now. (:
 
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top