question_answer

In an experiment of suspending spherical plastic balls in vertical turbulent jets of air and water it is found that if sphere is displaced slightly to left or right (from its suspended position), the air or water stream again pushes it back to its original position.

This can be explained by using

A) Archemedes' principle                 

B) Bernoulli's principle

C) Pascal's law       

D)        Stoke's theorem

Correct Answer: B

Solution :

The sphere shows stable equilibrium for small horizontal displacement because of velocity distribution of approaching fluid.

Near edge, velocity is low, so pressure is high. Hence, when ball is slightly displaced, it is pushed back to centre where velocity is more. As, by Bernoulli's principle where v is high, p is low.