A piston of a syringe pushes a liquid with a speed of 1 cm/sec. The radii of the syringe tube and the needle are R = 1cm and r = 0.5 mm respectively. The velocity of the liquid coming out of the needle is

Q: A piston of a syringe pushes a liquid with a speed of 1 cm/sec. The radii of the syringe tube and the needle are R = 1cm and r = 0.5 mm respectively. The velocity of the liquid coming out of the needle is
Fluid Mechanics

(A) 2 cm/sec
(B) 400 cm/sec
(C) 10 cm/sec
(D) None of these
Solution: According to the equation of continuity,
Av = av’
 v’ = (A/a)v
where A =πR2 and a = πr2
 v’= (R/r)2v = (1cm/0.05cm)(1 cm/sec) = 400 cm/sec.

Author: Rajesh Jha

QuantumStudy.com for CBSE|IIT-JEE|NEET

Leave a Reply