Fluid Mechanics GATE Quiz

When a body is placed over a liquid, it will sink down if

• Gravitational force is equal to the up-thrust of the liquid

• Gravitational force is less than the up-thrust of the liquid

• Gravitational force is more than the up-thrust of the liquid

• None of the above

A vertically immersed surface is shown in the below figure. The distance of its centre of pressure from the water surface is

• (bd²/12) + x̅

• (d²/12 x̅) + x̅

• b²/12 + x̅

• d²/12 + x̅

If cohesion between molecules of a fluid is greater than adhesion between fluid and glass, then the free level of fluid in a dipped glass tube will be

• Higher than the surface of liquid

• The same as the surface of liquid

• Lower than the surface of liquid

• Unpredictable

Dimensions of surface tension are

• ML°T⁻²

• ML°T

• ML r²

• ML²T²

A liquid compressed in cylinder has a volume of 0.04 m3 at 50 kg/cm² and a volume of 0.039 m3 at 150 kg/cm². The bulk modulus of elasticity of liquid is

• 400 kg/cm²

• 4000 kg/cm²

• 40 × 10⁵ kg/cm²

• 40 × 10⁶ kg/cm²

The loss of head due to friction in a pipe of uniform diameter in which a viscous flow is taking place, is (where RN = Reynold number)

• 1/RN

• 4/RN

• 16/RN

• 64/RN

A compound pipe of diameter d1, d2 and d3 having

lengths l1, l2 and l3 is to be replaced by an equivalent pipe of uniform diameter d and of the same length (l) as that of the compound pipe. The size of the equivalent pipe is given by

• l/d² = (l₁/d₁²) + (l₂/d₂²) + (l₃/d₃²)

• l/d³ = (l₁/d₁³) + (l₂/d₂³) + (l₃/d₃³)

• l/d⁴ = (l₁/d₁⁴) + (l₂/d₂⁴) + (l₃/d₃⁴)

• l/d⁵ = (l₁/d₁⁵) + (l₂/d₂⁵) + (l₃/d₃⁵)

The depth of centre of pressure of an immersed surface, inclined at an angle θ with the liquid surface lies at a distance equal to __________ the centre of gravity.

• IG sin²θ/Ax̅ below

• IG sin²θ/Ax̅ above

• IG sinθ/Ax̅ below

• IG sinθ/Ax̅ above

When a liquid is flowing through a pipe, the velocity of the liquid is

• Maximum at the centre and minimum near the walls

• Minimum at the centre and maximum near the walls

• Zero at the centre and maximum near the walls

• Maximum at the centre and zero near the walls

A piece weighing 3 kg in air was found to weigh 2.5 kg when

submerged in water. Its specific gravity is

• 1

• 5

• 7

• 6