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PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361338 Machine parts are jammed in winter due to

1 Increase in viscosity of lubricant

2 Decrease in viscosity of lubricant

3 Increase in surface tension of lubricant

4 Decrease in surface tension of lubricant

PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361339 A good lubricant must have

1 High viscosity

2 Low viscosity

3 High density

4 Low surface tension

PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361340 A thin plate of large area $A$ is placed midway in a gap of height $h$ filled with oil of viscosity $η_{0}$ and the plate is pulled at constant velocity $v$ by applying drag force on the plate. If a lighter oil of viscosity $η$ is then substituted in the gap, it is found that for the velocity $v$ , and the same drag force as previous case the plate is located unsymmetrically in the gap but parallel to the walls. Find $η$ in terms of distance from nearer wall to the plane $y$ .
supporting img

1

\frac{4 η_{0} y}{h}

2

\frac{4 η_{0} y}{h} [1 - \frac{y}{h}]

3

4 η_{0} [1 - \frac{y}{h}]

4

\frac{2 η_{0} y}{h}

Explanation:

Case I:
supporting img

Here viscous force acts on the plate on both sides
Drag force $= F_{1} + F_{2}$
$= [η_{0} \frac{v}{h / 2} + η_{0} \frac{v}{h / 2}] A = \frac{4 η_{0} v A}{h}$
Case II:

Drag force on the plate
$= [η \frac{v}{h - y} + η \frac{v}{y}] A = \frac{η v h A}{y (h - y)}$
As drag forces are equal
$\begin{aligned} \Rightarrow \frac{4 η_{0} v A}{h} = \frac{η v h A}{y (h - y)} \\ \Rightarrow η = \frac{4 η_{0} y}{h} [1 - \frac{y}{h}] \end{aligned}$

PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361341 From kinetic theory point of view viscosity represents transport of

1 Momentum

2 Mass

3 Energy

4 None of these

PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361342 Which of the following substances has the greatest viscosity?

1 Mercury

2 Water

3 Kerosene

4 Glycerine

PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361338 Machine parts are jammed in winter due to

1 Increase in viscosity of lubricant

2 Decrease in viscosity of lubricant

3 Increase in surface tension of lubricant

4 Decrease in surface tension of lubricant

PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361339 A good lubricant must have

1 High viscosity

2 Low viscosity

3 High density

4 Low surface tension

PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361340 A thin plate of large area $A$ is placed midway in a gap of height $h$ filled with oil of viscosity $η_{0}$ and the plate is pulled at constant velocity $v$ by applying drag force on the plate. If a lighter oil of viscosity $η$ is then substituted in the gap, it is found that for the velocity $v$ , and the same drag force as previous case the plate is located unsymmetrically in the gap but parallel to the walls. Find $η$ in terms of distance from nearer wall to the plane $y$ .
supporting img

1

\frac{4 η_{0} y}{h}

2

\frac{4 η_{0} y}{h} [1 - \frac{y}{h}]

3

4 η_{0} [1 - \frac{y}{h}]

4

\frac{2 η_{0} y}{h}

Explanation:

Case I:
supporting img

Here viscous force acts on the plate on both sides
Drag force $= F_{1} + F_{2}$
$= [η_{0} \frac{v}{h / 2} + η_{0} \frac{v}{h / 2}] A = \frac{4 η_{0} v A}{h}$
Case II:

Drag force on the plate
$= [η \frac{v}{h - y} + η \frac{v}{y}] A = \frac{η v h A}{y (h - y)}$
As drag forces are equal
$\begin{aligned} \Rightarrow \frac{4 η_{0} v A}{h} = \frac{η v h A}{y (h - y)} \\ \Rightarrow η = \frac{4 η_{0} y}{h} [1 - \frac{y}{h}] \end{aligned}$

PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361341 From kinetic theory point of view viscosity represents transport of

1 Momentum

2 Mass

3 Energy

4 None of these

PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361342 Which of the following substances has the greatest viscosity?

1 Mercury

2 Water

3 Kerosene

4 Glycerine

PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361338 Machine parts are jammed in winter due to

1 Increase in viscosity of lubricant

2 Decrease in viscosity of lubricant

3 Increase in surface tension of lubricant

4 Decrease in surface tension of lubricant

PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361339 A good lubricant must have

1 High viscosity

2 Low viscosity

3 High density

4 Low surface tension

PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361340 A thin plate of large area $A$ is placed midway in a gap of height $h$ filled with oil of viscosity $η_{0}$ and the plate is pulled at constant velocity $v$ by applying drag force on the plate. If a lighter oil of viscosity $η$ is then substituted in the gap, it is found that for the velocity $v$ , and the same drag force as previous case the plate is located unsymmetrically in the gap but parallel to the walls. Find $η$ in terms of distance from nearer wall to the plane $y$ .
supporting img

1

\frac{4 η_{0} y}{h}

2

\frac{4 η_{0} y}{h} [1 - \frac{y}{h}]

3

4 η_{0} [1 - \frac{y}{h}]

4

\frac{2 η_{0} y}{h}

Explanation:

Case I:
supporting img

Here viscous force acts on the plate on both sides
Drag force $= F_{1} + F_{2}$
$= [η_{0} \frac{v}{h / 2} + η_{0} \frac{v}{h / 2}] A = \frac{4 η_{0} v A}{h}$
Case II:

Drag force on the plate
$= [η \frac{v}{h - y} + η \frac{v}{y}] A = \frac{η v h A}{y (h - y)}$
As drag forces are equal
$\begin{aligned} \Rightarrow \frac{4 η_{0} v A}{h} = \frac{η v h A}{y (h - y)} \\ \Rightarrow η = \frac{4 η_{0} y}{h} [1 - \frac{y}{h}] \end{aligned}$

PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361341 From kinetic theory point of view viscosity represents transport of

1 Momentum

2 Mass

3 Energy

4 None of these

PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361342 Which of the following substances has the greatest viscosity?

1 Mercury

2 Water

3 Kerosene

4 Glycerine

PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361338 Machine parts are jammed in winter due to

1 Increase in viscosity of lubricant

2 Decrease in viscosity of lubricant

3 Increase in surface tension of lubricant

4 Decrease in surface tension of lubricant

PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361339 A good lubricant must have

1 High viscosity

2 Low viscosity

3 High density

4 Low surface tension

PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361340 A thin plate of large area $A$ is placed midway in a gap of height $h$ filled with oil of viscosity $η_{0}$ and the plate is pulled at constant velocity $v$ by applying drag force on the plate. If a lighter oil of viscosity $η$ is then substituted in the gap, it is found that for the velocity $v$ , and the same drag force as previous case the plate is located unsymmetrically in the gap but parallel to the walls. Find $η$ in terms of distance from nearer wall to the plane $y$ .
supporting img

1

\frac{4 η_{0} y}{h}

2

\frac{4 η_{0} y}{h} [1 - \frac{y}{h}]

3

4 η_{0} [1 - \frac{y}{h}]

4

\frac{2 η_{0} y}{h}

Explanation:

Case I:
supporting img

Here viscous force acts on the plate on both sides
Drag force $= F_{1} + F_{2}$
$= [η_{0} \frac{v}{h / 2} + η_{0} \frac{v}{h / 2}] A = \frac{4 η_{0} v A}{h}$
Case II:

Drag force on the plate
$= [η \frac{v}{h - y} + η \frac{v}{y}] A = \frac{η v h A}{y (h - y)}$
As drag forces are equal
$\begin{aligned} \Rightarrow \frac{4 η_{0} v A}{h} = \frac{η v h A}{y (h - y)} \\ \Rightarrow η = \frac{4 η_{0} y}{h} [1 - \frac{y}{h}] \end{aligned}$

PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361341 From kinetic theory point of view viscosity represents transport of

1 Momentum

2 Mass

3 Energy

4 None of these

PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361342 Which of the following substances has the greatest viscosity?

1 Mercury

2 Water

3 Kerosene

4 Glycerine

PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361338 Machine parts are jammed in winter due to

1 Increase in viscosity of lubricant

2 Decrease in viscosity of lubricant

3 Increase in surface tension of lubricant

4 Decrease in surface tension of lubricant

PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361339 A good lubricant must have

1 High viscosity

2 Low viscosity

3 High density

4 Low surface tension

PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361340 A thin plate of large area $A$ is placed midway in a gap of height $h$ filled with oil of viscosity $η_{0}$ and the plate is pulled at constant velocity $v$ by applying drag force on the plate. If a lighter oil of viscosity $η$ is then substituted in the gap, it is found that for the velocity $v$ , and the same drag force as previous case the plate is located unsymmetrically in the gap but parallel to the walls. Find $η$ in terms of distance from nearer wall to the plane $y$ .
supporting img

1

\frac{4 η_{0} y}{h}

2

\frac{4 η_{0} y}{h} [1 - \frac{y}{h}]

3

4 η_{0} [1 - \frac{y}{h}]

4

\frac{2 η_{0} y}{h}

Explanation:

Case I:
supporting img

Here viscous force acts on the plate on both sides
Drag force $= F_{1} + F_{2}$
$= [η_{0} \frac{v}{h / 2} + η_{0} \frac{v}{h / 2}] A = \frac{4 η_{0} v A}{h}$
Case II:

Drag force on the plate
$= [η \frac{v}{h - y} + η \frac{v}{y}] A = \frac{η v h A}{y (h - y)}$
As drag forces are equal
$\begin{aligned} \Rightarrow \frac{4 η_{0} v A}{h} = \frac{η v h A}{y (h - y)} \\ \Rightarrow η = \frac{4 η_{0} y}{h} [1 - \frac{y}{h}] \end{aligned}$

PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361341 From kinetic theory point of view viscosity represents transport of

1 Momentum

2 Mass

3 Energy

4 None of these

PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361342 Which of the following substances has the greatest viscosity?

1 Mercury

2 Water

3 Kerosene

4 Glycerine