Friction Test

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Friction Test - 5

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Weekly Quiz Competition

Question 1
1 / -0

The force of friction which opposes one surface to just slide over the other is called the

A
static friction

B
dynamic friction

C
rolling friction

D
limiting friction

Solution

The force of friction which opposes one surface to just slide over the other is called the limiting friction.
Question 2
1 / -0

When two smooth surfaces slide over each other, the friction

A
increases

B
decreases

C
remains the same

D
is absent

Solution

When two smooth surfaces slide over each other, the friction increases because the molecular forces between the molecules of the two surfaces increase. Thus, it increases the friction.
Question 3
1 / -0

Why is the shape of an aeroplane designed similar to the shape of a bird?

A
To increase fluid friction

B
To reduce fluid friction

C
To maintain fluid friction

D
To eliminate friction completely

Solution

The shape of an aeroplane is designed similar to the shape of a bird to reduce fluid friction.
Question 4
1 / -0

Which of the following instruments is used to measure force of friction?

A
Beam balance

B
Spring balance

C
Meter scale

D
Ordinary balance

Solution

Spring balance is used to measure the force of friction.
Question 5
1 / -0

Directions: Read the given data and answer the following question.

Make an inclined plane on a smooth floor and put a mark with pen at any point A on the inclined plane. Let a pencil cell move down from this point and note down the distance. Now, spread a piece of woolen cloth on the plane and repeat the experiment noting the distance. Repeat this activity by spreading sand paper over it.

In which case does the pencil cell covers maximum distance?

A
Distance covered would be same in all caases

B
When woolen cloth is spread over the plane

C
When sand paper is spread on the plane

D
When nothing is spread on the plane

Solution

When nothing is spread on the plane, the force of friction is minimum.
Question 6
1 / -0

Directions: Read the given data and answer the following question.

Make an inclined plane on a smooth floor and put a mark with pen at any point A on the inclined plane. Let a pencil cell move down from this point and note down the distance. Now, spread a piece of woolen cloth on the plane and repeat the experiment noting the distance. Repeat this activity by spreading sand paper over it.

In which case does the pencil cell covers minimum distance?

A
When woolen cloth is spread over the plane

B
When sand paper is spread on the plane

C
When nothing is spread on the plane

D
In all cases, distance covered is same

Solution

When woolen cloth is spread over the plane, it offers maximum frictional force. So, the distance covered by cell is minimum.
Question 7
1 / -0

When oils or other liquid lubricants cannot be used to reduce friction in a machine, then which of the following statements stands true?

A
An air cushion between the moving parts is used to reduce friction.

B
Gun powder is sprinkled between the moving parts of a machine.

C
The moving parts of the machines are made rough.

D
Both (1) and (3)

Solution

In some machines, it may not be advisable to use oil as lubricant. In such cases, an air cushion between the moving parts is used to reduce friction.
Question 8
1 / -0

How is static friction different from sliding friction?

A
When we try to move a surface, sliding friction comes into action. Static friction comes into play when objects are moving over each other.

B
Sliding friction comes into play when object stops moving and static friction comes into play when we move the object.

C
Sliding friction comes into play when object slides over another object. On the other hand, static friction comes into play when we try to move the object which is at rest.

D
Sliding friction is larger than static friction.

Solution

Sliding friction comes into play when object slides over another object. On the other hand, static friction comes into play when we try to move the object which is at rest.
Question 9
1 / -0

Anu runs her toy car firstly on dry marble floor, secondly on oily floor, thirdly on newspaper and fourthly on towel spread on the floor. Write the force of friction acting on the car on different surfaces in decreasing order.

A
Oily floor > dry marble floor > newspaper > towel

B
Towel > newspaper > dry marble floor > oily floor

C
Newspaper > towel > dry marble floor > oily floor

D
Oily floor > dry marble floor > towel > newspaper

Solution

Force of friction depends on the nature of surface in contact. The rougher the surface, the more is the friction between the surfaces in contact and vice-versa.
Towel > newspaper > dry marble floor > oily floor
Question 10
1 / -0

Why are brake pads used in the brake system of bicycles and automobiles?

A
To reduce friction

B
To increase friction

C
To reduce normal force

D
To prevent wearing of wheels

Solution

We deliberately increase friction by using brake pads in the brake system of bicycles and automobiles. When you are riding a bicycle, the brake pads do not touch the wheels. But when you press the brake lever, these pads arrest the motion of the rim due to friction and the wheel stops moving.
Question 11
1 / -0

Directions: Read the following statements carefully and answer the question given below.

(i) We are able to walk because of friction.
(ii) Friction between tip of a pen and a paper allows us to write.
(iii) Friction between the different parts of machines produces heat.

Which of the above statements is incorrect?

A
Only (i)

B
Only (ii)

C
Only (iii)

D
None of these

Solution

All the three statements are correct.
Question 12
1 / -0

Why is it easier moving a box already in motion than a box at rest?

A
Because sliding friction is equal to static friction

B
Because sliding friction is greater than static friction

C
Because sliding friction is lesser than static friction

D
Because sliding friction and static friction become zero

Solution

When a box starts sliding, the contact points on its surface do not get enough time to lock into the contact points on the floor. So, sliding friction is slightly lesser than static friction. Thus, it is easier moving a box already in motion than a box at rest.
Question 13
1 / -0

Under which of the following phases of its flight, will a helicopter experience the maximum drag from air?

A
When it is lifting off

B
When it is moving forward at a high speed

C
When it is hovering on top of a river without moving

D
When it is coming down while landing

Solution

When a helicopter is hovering, its horizontal or vertical motion is zero. Hence, it experiences no drag. A helicopter takes off and lands vertically at not a very high speed. Hence, it experiences little drag during these two phases. Only when it is moving at a high speed, it will experience the highest drag from air.
Question 14
1 / -0

It is difficult to drag a bucket full of water than an empty bucket because

A
force of friction decreases as we drag a bucket full of water

B
force of friction increases with the increase of normal force due to increased weight

C
force of friction increases with the decrease of normal force due to increased weight

D
force of friction is independent of the weight of the body

Solution

The force of friction increases with the increase of normal force. Therefore, it is difficult to drag a bucket full of water than an empty bucket.
Question 15
1 / -0

A bicycle is in motion. The force of friction exerted by the ground on its wheel is such that it acts

A
in backward direction on the front wheel and in forward direction on the rear wheel when it is accelerating

B
in forward direction on the front wheel and in backward direction on the rear wheel when brakes are applied on the rear wheel only

C
in backward direction on the front wheel and in forward direction on the rear wheel when brakes are applied on the rear wheel only

D
in backward direction on both the wheels when brakes are applied on both the wheels

Solution

When cycle accelerates, the rear wheel accelerates forward due to rotation. Hence, friction is forward. The front wheel tries to accelerate translationally without rotational motion hence friction is backward.
When breaks are applied to the rear wheel, the conditions are reversed.
If breaks are applied on both wheels, they try to skid over the road in forward direction. Hence, friction is in the backward direction for both the wheels.

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Re-Attempt Weekly Quiz Competition

Friction Test - 5

Result

Friction Test - 5

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SHARING IS CARING

Question 1

static friction

dynamic friction

rolling friction

limiting friction

Solution

Question 2

increases

decreases

remains the same

is absent

Solution

Question 3

To increase fluid friction

To reduce fluid friction

To maintain fluid friction

To eliminate friction completely

Solution

Question 4

Beam balance

Spring balance

Meter scale

Ordinary balance

Solution

Question 5

Distance covered would be same in all caases

When woolen cloth is spread over the plane

When sand paper is spread on the plane

When nothing is spread on the plane

Solution

Question 6

When woolen cloth is spread over the plane

When sand paper is spread on the plane

When nothing is spread on the plane

In all cases, distance covered is same

Solution

Question 7

An air cushion between the moving parts is used to reduce friction.

Gun powder is sprinkled between the moving parts of a machine.

The moving parts of the machines are made rough.

Both (1) and (3)

Solution

Question 8

When we try to move a surface, sliding friction comes into action. Static friction comes into play when objects are moving over each other.

Sliding friction comes into play when object stops moving and static friction comes into play when we move the object.

Sliding friction comes into play when object slides over another object. On the other hand, static friction comes into play when we try to move the object which is at rest.

Sliding friction is larger than static friction.

Solution

Question 9

Oily floor > dry marble floor > newspaper > towel

Towel > newspaper > dry marble floor > oily floor

Newspaper > towel > dry marble floor > oily floor

Oily floor > dry marble floor > towel > newspaper

Solution

Question 10

To reduce friction

To increase friction

To reduce normal force

To prevent wearing of wheels

Solution

Question 11

Only (i)

Only (ii)

Only (iii)

None of these

Solution

Question 12

Because sliding friction is equal to static friction

Because sliding friction is greater than static friction

Because sliding friction is lesser than static friction

Because sliding friction and static friction become zero

Solution