The diagram shows a pipe of uniform cross section in which water is flowing. The directions of flow and the volume flow rates in cm³/s are shown for various portions of the pipe. The direction of flow and the volume flow rate in the portion marked A are:
Correct answer: D. ↓ and 15 cm³/s
- A. ↓ and 3 cm³/s
- B. ↑ and 7 cm³/s
- C. ↑ and 11 cm³/s
- D. ↓ and 15 cm³/s
Explanation
applying conservation of volume at the junction (total flow in= total flow out). Flows into the junction: 6 (from left) + 3(top left downward) + 5 (top right downward) + 4 (frombottom right upward into junction) = 18 cm³/s into thejunction. Flows out of the junction: 3 (to the right) + flowthrough A. So flow through A = 18 − 3 = 15 cm³/s, and it mustbe leaving the junction (i.e. downwards) to balance the others.
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