Two pipes: one is 2 cm wide, the other is 4 cm. In the 2 cm pipe, the water speed is:
Correct answer: A. 4 times faster
- A. 4 times faster
- B. 1/4 times slower
- C. 2 times faster
- D. Half as fast
Explanation
If the diameter is halved, the cross-sectional area scales with diameter², so the area reduces by a factor of 4; continuity requires the velocity increase by a factor of 4 in the narrower pipe.
Report an error
The more specific you are, the faster it gets fixed. A source beats an opinion.
Prefer email? [email protected]
About Fluid Dynamics
Fluid flow is described through speed, pressure and density, including steady flow and the equation of continuity for conserving mass. Bernoulli's equation relates pressure, speed and height, while fluid drag and terminal velocity explain why a falling object eventually moves at constant speed when drag balances its weight.
Practise Fluid Dynamics
366 free Fluid Dynamics MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Discussion
Stuck on an option, or know a faster way to get there? Ask or explain it here.
No comments yet. Be the first to explain this one.
Exams that ask Physics questions like this
Physics is on 16 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
More Fluid Dynamics questions
When will liquid flow in a pipe be most smooth (streamline)?
An iceberg of density 900 Kg/m3 is floating in water of density 1000 Kg/m3. The percentage of the volume of the iceberg outside the water is
The pressure at the bottom of a tank containing a liquid does not depend on?
Water flows steadily through a pipe of uniform cross-section from point A to B with same speed in these positions:
Water flows at 5.18 m/s in a pipe with area 4.20 cm². The pipe goes down and gets wider to 7.60 cm². What's the new speed?
Kerosene oil moves at 5 m/s. What's the velocity head? (g = 10 m/s²)