Question

Water is flowing through a pipe of uniform cross-section under constant pressure. At some place the pipe becomes narrow, the pressure of water at this place:

• A. increases
• B. decreases
• C. remains unchanged
• D. depends on several factors

Answer 1

The correct option is B decreases

Given, That area of cross section at initial point is more than the final point,

From the equation of continuity, we can say that velocity at the final point is more than initial point.

Bernoulli theorem states that $P+dgh+\frac{1}{2}d{v}^2=constant$

At final point, the velocity is more, so the pressure will be less.

Therefore the pressure decreases,

So the correct option is $B$