Tag: viscosity

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Questions Related to viscosity

Multiple choice viscosity option b: engineering physics properties of matter physics

Viscosity is most closely related to:

  1. density

  2. velocity

  3. friction

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

Viscosity is the property by virtue of which a liquid offers resistance for the relative motion between liquid molecules. Friction is the force which opposes relative motion between any two objects. So, viscosity is most closely related to friction.

Multiple choice viscosity option b: engineering physics properties of matter physics

Viscosity of the fluids is analogous to:

  1. Random motion of the gas molecules

  2. Friction between the solid surfaces

  3. integral motion

  4. Nonuniform motion of solids
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Viscosity is the property by virtue of which a liquid offers resistance for the relative motion between its layer.
Friction is the force between two solid surfaces which offers resistance for the relative motion between them. 
So, viscosity of the fluids is analogous to friction between the solid surfaces.

Multiple choice viscosity option b: engineering physics properties of matter physics

The main cause of viscosity is:

  1. force of repulsion between molecules.

  2. cohesive forces.

  3. adhesive forces.

  4. both cohesive and adhesive forces.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When the inter-molecular forces of attraction are strong within a liquid, there is a viscosity. Cohesive forces are attractive forces exist between molecules of the same substance. So, cohesive forces are the main cause of viscosity. Adhesive forces are attractive force between unlike molecules.

Multiple choice viscosity option b: engineering physics properties of matter physics

The arrow with a pointed tip can move faster in air than that of with a blunt tip.

  1. True

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

The arrow with  a pointed tip can move faster in air than that of with a blunt tip because blunt tip arrow has more area of cross section , so it requires more amount of force to create the same amount of pressure as that by the pointed tip .

so given statement is true  , hence option (A) is correct

Multiple choice viscosity option b: engineering physics properties of matter physics

Viscosity is the property by virtue of which a liquid:

  1. occupies minimum surface area.

  2. offers resistance for the relative motion between its layers.

  3. becomes spherical in shape.

  4. tends to gain its deformed position.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Viscosity is the property by virtue of which a liquid offers resistance for the relative motion between it's layer because it's main cause is cohesive force which acts between like molecules and try to bind them. So, it offers resistance for relative motion between liquid molecules.

Multiple choice viscosity option b: engineering physics properties of matter physics

The cause of viscosity of liquid is:

  1. diffusion.

  2. adhesive force.

  3. gravitational force.

  4. cohesive force.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Due to strong cohesive forces between the molecules, any layer in a moving fluid tries to drag the adjacent layer to move with an equal speed and thus produces the effect of viscosity.

Multiple choice viscosity option b: engineering physics properties of matter physics

The viscous drag is:

  1. inversely proportional to the velocity gradient.

  2. directly proportional to the surface area of layers in contact.

  3. independent of nature of liquid.

  4. perpendicular to the direction of liquid flow.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The viscous drag force can be written as below:
$F =  \eta \ A \ (\cfrac{dV}{dX})$ where, F is viscous drag force (or tangential force)
$\eta$ is coefficient of viscosity
$A$ is surface area of layers in contact
$\dfrac{dV}{dX} $ is velocity gradient
$\eta$ is property of liquid.
So, we can see that drag is directly proportional to the velocity gradient, surface area and nature of liquid. Drag force acts in opposite direction of liquid flow.