Concept:When the valve is opened, the pressure energy of the stationary liquid is converted into kinetic energy of the flowing water.
This conversion is described by Bernoulli’s principle for flow at the same height.
Explanation:Initially, the pipe is closed, so the liquid is at rest and the gauge reads the static pressure
P1.
After the valve is opened, the water flows out, and part of the pressure energy is transformed into kinetic energy, reducing the pressure to
P2.
Applying Bernoulli’s equation for the same horizontal level:
P1=P2+21ϱv2Here,
ϱ is the density of water and
v is the speed of outflow.
Rearranging gives:
P1−P2=21ϱv2Solving for
v:
v2=ϱ2(P1−P2)v=[ϱ2(P1−P2)]21Answer:The speed of water flowing out is:
v=[ϱ2(P1−P2)]21Therefore, the correct option is
Option B.