Question

A cylinder of height 20 m is completely filled with water. The velocity of efflux of water in m/s through a small hole on the side will of the cylinder near its bottom is 

(A) 10 

(B) 20 

(C) 25.5 

(D) 5

Answer 1

Correct option: (B) 20

Explanation:

Way 1: stored PE = KE in motion

∴ mgh = (1/2) mV² 

∴ 2gh = V² 

Given : n = 20 m

 ∴ V² = 10 × 20 × 2

V² = 400

V = 20 m/s

Way 2:

Bernoulli's theorem just inside & outside hole

P_inside + ρgh + 0 = P_outside + (ρV² / 2)

ρ × 10 × 20 = ρ × (V² / 2)

V² = 400

V = 20 m/s