A submarine which may be supposed to approximate a cylinder 3 m in diameter and 15 m long travels submerged at 1.54 m/s in sea water at 4°C. What is the drag exerted on it? (Take C_d = 0.7 and ρ = 1025 kg/m³)

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Question

This question was previously asked in

UPSC ESE (Prelims) Civil Engineering 19 Feb 2023 Official Paper

Answer 1

Concept:

Drag Force,

\(F_D=C_D\times \frac{1}{2}\times \rho AV^2\)

where,

C_D = coefficient of drag

\(\rho=\) density of fluid

A = area

V = velocity

Calculation:

Given data

C_D = 0.7

A = \(15\times3=45m^2\)

V = 1.54 m/s

Drag force

\(F_D=0.7\times \frac{1}{2}\times1025\times45\times1.54^2=38287N\)