Why is the velocity of flow six times bigger in a tube with a larger radius?

AI Thread Summary
The discussion revolves around a fluid dynamics question regarding the velocity of water flow in tubes of different radii. The original tube has a radius of 1 cm, and the question asks for the flow velocity in a section with a radius of 3 cm. Participants note that the problem may be flawed, as the provided answer choices do not seem to align with the principles of fluid flow. They emphasize the importance of showing working and using relevant equations, such as the continuity equation, to analyze the flow rates and velocities. The conversation highlights the need for clarity in problem statements and the application of fluid dynamics principles for accurate solutions.
BrnoStudent
Messages
7
Reaction score
0
Water flows through a rigid tube, the radius of which is 1 cm. What will be the velocity
of flow in a part of the tube with a radius of 3 cm?

Please show your working and any equations that you use, no matter how basic you think it is. If there is no working to show then just explain how you arrived at your answer. I know the answer is e, I just don't know why.
I have an exam on tuesday and this is a practice question. Thank you.
a) 3 m.s-1
b) one third of the original value
c) one sixth of the original value
d) three-times bigger than the original value
e) six-times bigger than the original value
 
Physics news on Phys.org
BrnoStudent said:
Water flows through a rigid tube, the radius of which is 1 cm. What will be the velocity
of flow in a part of the tube with a radius of 3 cm?

Please show your working and any equations that you use, no matter how basic you think it is. If there is no working to show then just explain how you arrived at your answer. I know the answer is e, I just don't know why.
I have an exam on tuesday and this is a practice question. Thank you.
a) 3 m.s-1
b) one third of the original value
c) one sixth of the original value
d) three-times bigger than the original value
e) six-times bigger than the original value

Something's fishy with the problem as posted; For the given information I don't see a valid answer amongst the choices. Check and confirm the problem statement.

Also, you need to show some attempt at the problem before we can know how to help; don't ignore the posting template, it's there for a reason.

What equations do you know that involve fluid flow, particularly ones involving flow rates and velocities? List them.
 
gneill said:
Something's fishy with the problem as posted; For the given information I don't see a valid answer amongst the choices. Check and confirm the problem statement.

Also, you need to show some attempt at the problem before we can know how to help; don't ignore the posting template, it's there for a reason.

What equations do you know that involve fluid flow, particularly ones involving flow rates and velocities? List them.

As much as I would like to have a tête à tête about the above question, I don't have the time. I also have an anatomy exam, medical cemistry and biology exam this week as well. The way the question was on the paper is the way I typed it. If it is an impossible question, then thanks for all your help.
 
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