Question

A given shaped glass tube having uniform cross section is filled with water and is mounted on a rotatable shaft as shown in figure. If the tube is rotated with a constant angular velocity $\omega$ when

• A. water levels in both sections A and B go up
• B. water level in section A goes up and that in B comes down
• C. water level in section A comes down and that in B it goes up
• D. water levels remain same in both sections

Answer 1

Answer: (A)

According to Bernoulli's principle
$P+\frac{1}{2} \rho v^{2}=$ constant
At the sides the velocity is higher, so the pressure is lower. But the pressure at a given horizontal level must be equal therefore the liquid rises at the sides to some height to compensate for this drop in pressure.