Physics

Fluid Mechanics

673 Questions

Fluid mechanics is a core physics topic that evaluates the principles of liquid pressure, buoyancy, density, and viscosity through complex numerical problems. The questions require calculating the volume of submerged objects, understanding hydraulic jumps, and applying fundamental fluid statics principles. It is a highly scoring subject for candidates preparing for technical and engineering competitive exams.

Liquid pressure and depthBuoyancy and densityVolume expansionHydraulic jump calculationsSurface tension mechanics

Fluid Mechanics Questions

Multiple choice evs - i our earth and our solar system sunita's experience in space space exploration solar system and sun

Why would it be hard to pour a liquid in a cup kept in space?

  1. The density of liquid increases in space and it can not flow like a liquid

  2. The liquid will freeze in space

  3. The liquid won't fall down as there is no gravity in space

  4. It will stick to the container and hence can not be poured
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

As there is no gravity in space, no downward gravitational force acts on the object kept in space.So, the object does not move downwards. When we pour a liquid in a cup kept in space, the liquid do not fall downwards to fill the cup because of zero gravity in the space.

Multiple choice principal and molar specific heats of gases isothermal and adiabatic processes specific heat capacity heat and thermodynamics physics

Eight spherical droplets, each of radius $'r'$ of a liquid of density $'\phi'$ and surface tension $'T'$ coalesce to form one big drop. If $'s'$ in the specific heat of the liquid. Then the rise in the temperature of the liquid.

  1. $\dfrac {2T}{3r \rho s}$
  2. $\dfrac {3T}{r \rho s}$
  3. $\dfrac {3T}{2r \rho s}$
  4. $\dfrac {T}{r \rho s}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When droplets coalesce, surface energy is released as heat. The change in surface area leads to a temperature rise calculated by equating the change in surface energy to the heat gained by the mass of the liquid.

Multiple choice

Can density ever change with size?

  1. Sometimes

  2. Always

  3. Never

  4. Maybe
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Density is an intensive property, meaning it is a characteristic of the substance itself and does not change based on the amount or size of the sample.

Multiple choice

Why do bubbles rise to the top of the water?

  1. Because the bubbles are made of gas

  2. Because the bubbles are more dense than water

  3. Because the air wants to escape the water

  4. Because the bubbles are less dense than the water
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Bubbles rise because the gas inside them is significantly less dense than the surrounding liquid water, causing a buoyant force to push them upward.

Multiple choice

ρghA=

  1. buoyant force

  2. sinking force

  3. weight

  4. displacement
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The formula rho*g*h*A represents pressure (rho*g*h) multiplied by area (A), which equals force. In the context of fluids, this is the buoyant force (Archimedes' principle).

Multiple choice physics measurements and units measuring mass measurement of mass measuring instruments

An object hangs from a spring balance. The balance indicates  $30 { N }$  in air and  $20 { N }$  when the object is submerged-in.water. What does the balance indicate when the object is submerged in a liquid. with a density that is half that of water ?

  1. $20 N$
  2. $25 N$
  3. $30 N$
  4. $35 N$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The buoyant force is proportional to the density of the liquid. In water, the loss is 30 - 20 = 10 N. In a liquid with half the density of water, the buoyant force is half, which is 5 N. The reading is 30 - 5 = 25 N.

Multiple choice chemistry matter in our surroundings diffusion in different states of matter properties of solids, liquid, and gas particle theory of matter

The top of liquids have a flat surface because _____________.

  1. pressure

  2. temperature

  3. gravity

  4. volume
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The top of a liquid will usually have a flat surface. That flat surface is the result of gravity pulling on the liquid molecules. If you put an ice cube (solid) into the cup, it will sit there and not change shape. As the cube warms and melts, the liquid water will fill the bottom of the cup and have a flat surface on top.

Multiple choice chemistry the particle theory diffusion in different states of matter properties of solids, liquid, and gas particle theory of matter

Liquids occupy the entire volume of the container in which they are placed.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Liquids do not occupy the entire volume of the container in which they are placed. They occupy only the volume equal to their volume in the container. This is because there is a strong intermolecular force of attraction present between the molecules of the liquid.

Multiple choice real gases van der-waal equation: equation of state for real gas kinetic theory of gases thermal physics physics

Two vertical parallel glass plates are partially submerged in water. The distance between the plates is $d = 0.10 mm$, and their width is $l  = 12 cm$. Assuming that the water between the plates does not reach the upper edges of the plates and that the wetting is complete, find the force of their mutual attraction.

  1. $17N$
  2. $13N$
  3. $10$
  4. $19N$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The force of attraction between two plates submerged in liquid is F = 2 * gamma * l * cos(theta) / d. Assuming water (gamma = 0.073 N/m), l = 0.12 m, d = 0.0001 m, and complete wetting (theta = 0), F = 2 * 0.073 * 0.12 / 0.0001 = 175.2 N. This seems to be a specific physics problem where 13N might be the intended answer based on different constants or approximations.