Friction Test

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Friction Test - 23

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Weekly Quiz Competition

Question 1
1 / -0

Friction is not required in which of the following cases?

A
Man running on the ground.

B
Friction between parts of a machine.

C
Writing with a pen.

D
Monkey climbing a tree.

Solution

A) If there is no friction between man and ground then man will slip/ fall.
B) If there is no friction between parts of machine then there is no loss of energy and work efficiency increases.
C) If friction is not present between pen and copy then we cannot write properly.
D) Friction is required for a monkey to climb on tree otherwise it will slip down.
Hence Option B
Question 2
1 / -0

Frictional force is nearly negligible on :

A
Rough surfaces

B
Semi-smooth surfaces

C
Smooth surfaces

D
None of these

Solution

On smooth surfaces due to lack of uneveness their is no resistance to motion of the body hence their is no frictional force.
Question 3
1 / -0

Driving a car on a wet road is difficult because water

A
makes it difficult to turn the car.

B
decreases the friction between the tyres and the road.

C
increases the friction between the tyres.

D
makes friction between the road and tyres zero.

Solution

We know that greater the friction more is the ease of driving. Water decreases the friction between the tyres of a vehicle and the road hence, driving a car on a wet road is difficult.
Question 4
1 / -0

If rough surface is polished beyond a certain limit than the magnitude of frictional force will

A
Nothing can be said.

B
sometime increases and sometime decreases.

C
increase.

D
decrease.

Solution

Friction decreases with smoothness only to a certain degree. When the surfaces are further polished, the Vander Waal forces and electrostatic forces between the atoms of the surfaces increases, this happens because the surfaces come closer when polished.
Question 5
1 / -0

From following statements choose the correct combination.
A. Grease is used to reduce friction in bicycle chain
B. Ball bearings are used to reduce friction in a fan
C. Oil can be used to increase friction in a car engine.
D. Talc can be used to reduce friction when an object is sliding on a surface.

A
A, B, D

B
A, C, D

C
B, C, D

D
A, B, C

Solution

Friction is reduced by using oil, grease, ball bearings and talc.
Because by the use of this things, the surface becomes smooth and therefore it helps in reducing the force of friction.
Question 6
1 / -0

In which of the following cases the net force is not equal to zero?

A
A kite.skillfully held stationary in the sky

B
A ball falling freely from a height

C
A helicopter hovering above the ground

D
A cork floating on the surface of water

Solution

a ball freely falling from a height is not experiencing zero net force ,as the ball is constantly experiencing a gravitational force from earth and also accelerating by amount 'g' constantly.
(B) is correct.
All other case contain objects in stationary phase hence zero acceleration , zero net force.
Question 7
1 / -0

The application of decreasing friction includes :

A
Ball bearing used in moving parts of a machine

B
The streamlined shape of an aircraft

C
The layer of air between the hull of a hovecraft.

D
All of the above

Solution

Friction opposes the relative motion between two surfaces in contact. Friction is sometimes undesirable.
Friction can be reduced by:
i. using ball bearings in moving parts of the machine.
ii. giving suitable shapes to bodies moving in fluids. For example, the streamlined shape of an aircraft
iii. using air cushion between the moving parts. For example, the layer of air between the hull of a hovercraft.
Question 8
1 / -0

Which of the following activity would not be possible in the absence of friciton?

A
holding a glass

B
writing on a paper

C
sitting on a chair

D
all of the above

Solution
Question 9
1 / -0

The friction of the surface of a wooden bench can be increased by;

A
rubbing it with sand paper.

B
using lubricants like oil and grease.

C
using powder lubricants.

D
grinding or polishing the surface.

Solution

When the surface of the wooden bench rubbed with sand paper then more roughness will appear on the surface hence it increase the friction of the surface of wooden bench.
Question 10
1 / -0

What would happen to a moving object if there would be no friction?

A
The object will stop

B
The object will keep moving

C
The object will change speed

D
The object will change direciton

Solution

An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.Friction oppose relative motion. In its absence, a moving object will not stop.
Answer (B) the object will keep moving

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Re-Attempt Weekly Quiz Competition

Friction Test - 23

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Friction Test - 23

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SHARING IS CARING

Question 1

Man running on the ground.

Friction between parts of a machine.

Writing with a pen.

Monkey climbing a tree.

Solution

Question 2

Rough surfaces

Semi-smooth surfaces

Smooth surfaces

None of these

Solution

Question 3

makes it difficult to turn the car.

decreases the friction between the tyres and the road.

increases the friction between the tyres.

makes friction between the road and tyres zero.

Solution

Question 4

Nothing can be said.

sometime increases and sometime decreases.

increase.

decrease.

Solution

Question 5

A, B, D

A, C, D

B, C, D

A, B, C

Solution

Question 6

A kite.skillfully held stationary in the sky

A ball falling freely from a height

A helicopter hovering above the ground

A cork floating on the surface of water

Solution

Question 7

Ball bearing used in moving parts of a machine

The streamlined shape of an aircraft

The layer of air between the hull of a hovecraft.

All of the above

Solution

Question 8

holding a glass

writing on a paper

sitting on a chair

all of the above

Solution

Question 9

rubbing it with sand paper.

using lubricants like oil and grease.

using powder lubricants.

grinding or polishing the surface.

Solution

Question 10

The object will stop

The object will keep moving

The object will change speed

The object will change direciton

Solution

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