Question

As water flows from a low elevation to a higher elevation through a pipe that changes in diameter,

(a) The water pressure will increase.

(b) The water pressure will decrease.

(c) The water pressure will stay the same.

(d) Need more information to determine how the water pressure changes.

Short answer

The correct option is (d) need more information to determine how the water pressure changes.

Step-by-step solution

Understanding the piezometric head

The term piezometric head is a very useful concept that is described as the addition of a pressure head and datum head. The direction of flow of a liquid through a pipe/tube decides with the help of a piezometric head.

Explaining Bernoulli’s equation

The expression of Bernoulli’s can be represented as,

Here, p is the water pressure, ρ is the liquid density, g is the gravitational acceleration, v is the liquid velocity, z is the datum, c is a constant and (p/ρ g +z) is the piezometric head.

The water pressure depends on the cross-sectional area of the pipe, but here the variation of diameter of the pipe is not mentioned in the question, so the variation of water pressure would not obtain.

So, need more information to determine how the water pressure changes.

Thus, from the above analysis, option (d) is correct.