Moderate

According to equation of continuity when water falls its speed increases while its cross sectional area

Correct answer: B. Decreases

  • A. Increases
  • B. Decreases
  • C. Same
  • D. Different

Explanation

The equation of continuity states that A1V1 = A2V2, where A is the cross-sectional area and V is the fluid velocity. This implies that for a constant flow rate, an increase in fluid speed (V) must result in a decrease in cross-sectional area (A). Thus, when water falls and its speed increases, the cross-sectional area must decrease. Option B is correct because it accurately reflects this relationship. Options A and C are incorrect because they would not maintain the continuity of flow. Option D is incorrect due to its ambiguity.

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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.

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