Friction Test

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Friction Test - 11

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Weekly Quiz Competition

Question 1

1 / -0

Use the following information to answer the next question.

A box is placed on three different surfaces − a marble floor, a cardboard sheet, and a sand paper. The minimum forces required to simply move the box on the surfaces are F_m, F_c, and F_s respectively.

The three forces can be arranged in the decreasing order as

F_c < F_m < F_s

F_c < F_s < F_m

F_m < F_c < F_s

F_s < F_c < F_m

Solution

When a body that is resting on a surface is moved along the surface, friction is generated between the two contact surfaces. The minimum force required to simply move the body is equal to the magnitude of the generated friction. The friction offered by a marble floor is less than that offered by a cardboard sheet and sandpaper. Again, the friction offered by a cardboard sheet is less than that offered by a sandpaper. Hence, the minimum forces required to simply move the box on the different surfaces are related as F_m < F_c < F_s.

The correct answer is C.

Question 2

1 / -0

Use the following information to answer the next question.

Pappu is applying a large force in order to push a heavy box lying on the floor. Then, his younger brother, Chintu spreads a little bit of oil on the floor. Now, Pappu feels that it has become relatively easier to move the box.

This happens because the

oil magnifies the applied muscular force

oil reduces the friction between two surfaces

application of oil generates an upward thrust

application of oil reduces the gravitational force

Solution

Oil is one of the best lubricants. The application of lubricants between two moving surfaces reduces the friction between them. Since friction always opposes motion, the resistance against the motion of the given box is reduced on the oil-spread floor. Hence, Pappu can push the box by applying a relatively lesser muscular force.

The correct answer is B.

Question 3

1 / -0

Use the following information to answer the next question.

Friction has advantages as well as disadvantages. Dilip prepares a list of some of the advantageous applications of friction, as shown in the given table.

Application of friction

I Walking

II Writing

III Wearing out of shoes

IV Igniting a matchstick

V Gripping an object

Which of the items listed in the given table is not an advantage of friction?

II

III

IV

V

Solution

Friction plays an important role in life. Friction has disadvantages as well as advantages. One of the disadvantages of friction is the wearing out of shoes when used for a long time. The reason for this is the heat developed by friction between the shoes and the ground surface while walking.

The correct answer is B.

Question 4
1 / -0

If the force of friction were not to exist, then it would be almost impossible to both

A
speak and listen

B
write and walk

C
speak and walk

D
write and listen

Solution

Friction is an important aspect of life. We are able to walk on a surface because of the presence of friction between the ground surface and our feet. If friction were to become zero, then the act of walking would become impossible, causing us to slip and fall.

One is able to write on a surface (for example, a blackboard) only if friction is present on the surface. We are able to write on a blackboard because of the presence of friction between the board and the chalk.

The correct answer is B.
Question 5
1 / -0

Lubricants are used to increase the efficiency and reduce the wear and tear of machines. The application of lubricants between machine parts helps to

A
reduce friction

B
develop more heat

C
increase gravitational force

D
change atmospheric pressure

Solution

Lubricants are thick, oily liquids. They cause two surfaces to easily slip on one another. This is because they reduce the friction between the two surfaces by creating a smooth layer between them. When lubricants are applied between two machine parts that are moving in contact with each other, the friction between them is reduced. This helps the machine parts to move faster without much wear and tear, thereby enhancing the efficiency of the machine.

The correct answer is A.
Question 6
1 / -0

The sides of matchboxes are made rough so as to

A
hold them easily

B
reduce their cost

C
make them strong

D
increase their friction

Solution

The roughness over a surface increases its friction. Sparks are produced when a matchstick is rubbed against the rough surface of a matchbox. This is caused by the large friction produced between the matchstick and the box. Hence, the sides of matchboxes are made rough.

The correct answer is D.

Question 7

1 / -0

Use the following information to answer the next question.

Ram and Shyam are pushing two identical boxes. Ram is pushing box I that is placed on a wheel cart, while Shyam is pushing box II that is placed on the ground. Both Ram and Shyam are trying to maintain a steady motion of the boxes.

It is relatively difficult for Shyam to maintain a steady motion of box II because

sliding friction is greater than rolling friction

rolling friction is greater than sliding friction

static friction is greater than sliding friction

sliding friction is greater than static friction

Solution

Sliding friction is always greater than rolling friction. Box II is sliding on the ground because of the force applied by Shyam. Box I is rolling on wheels because of the force applied by Ram. Hence, Shyam has to apply a greater force to maintain a steady motion of his box.

The correct answer is A.

Question 8
1 / -0

Which of the following actions does not increase friction?

A
Threading tires

B
Grinding on stones

C
Making spikes on shoes

D
Powdering a carom board

Solution

The friction of a surface is increased by increasing its roughness. The roughness of a carom board does not increase when it is powdered. Hence, the friction of a carom board surface does not increase when it is powdered.

The correct answer is D.
Question 9
1 / -0

X is a physical quantity that decreases with the use of any lubricants between two surfaces. What does X represent?

A
Temperature

B
Pressure

C
Friction

D
Density

Solution

Lubricants are thick liquids that make rough surfaces smooth and slippery. The application of lubricants reduces the friction between two surfaces moving relative to each other. Since the use of lubricants between two surfaces reduces the value of X, X must be the force of friction.

The correct answer is C.

Question 10

1 / -0

Use the following information to answer the next question.

Three statements regarding friction.

I Friction is caused by the irregularities of the contact surfaces.

II It is easier to push a moving object than it is when the same object at

rest.

III For a given surface, friction remains the same, whatever be the mass of the object placed on it.

Among the given statements,

only I is correct

only III is correct

both I and II are correct

both II and III are correct

Solution

Friction is the result of the interlocking between two rough surfaces moving or trying to move with respect to each other. All surfaces have some irregularities that cause friction. Hence, statement I is correct.

It is the kinetic friction that acts when an object is moving. Kinetic friction is always less than static friction. Hence, it is easier to push a moving object than it is when the same object at rest. Hence, statement II is also correct.

For a given surface, friction always depends on the mass of the body over it. The heavier the object, the more is the friction between the surfaces. Therefore, statement III is incorrect.

The correct answer is C.

Question 11
1 / -0

In order to move a stationary object, an interlocking between the two surfaces must be overcome. The minimum force required to overcome this interlocking is known as

A
static friction

B
rolling friction

C
sliding friction

D
kinetic friction

Solution

Static friction is the measure of the minimum force required to overcome the interlocking between two surfaces in contact, to move one over the other.

The correct answer is A.

Question 12

1 / -0

Use the following information to answer the next question.

Four similar boxes are labelled I, II, III, and IV. The masses of I and III are equal and the masses of II and IV are equal. The mass of box I is smaller than that of box II. Boxes I and II are placed in a grass field and boxes III and IV are placed on a marble floor.

Which box requires the maximum force to be moved?

I

II

III

IV

Solution

Irregularities on surfaces offer resistance to the motion of an object over it. This resistance is called friction. The more the irregularities on the surface, the more is the friction. Hence, more force is required to move an object placed on an irregular surface. Since irregularities present on a grass field are more than those present on a marble floor, more force is required to move a box placed in the grass field. Boxes I and II are placed in a grass field. Therefore, boxes I and II require more forces to be moved than those required by boxes III and IV.

The opposing force of friction does not remain the same for heavier and lighter objects. Frictional force is greater for heavier objects and smaller for lighter objects. Since box II is heavier than box I, box II requires the maximum force to be moved.

The correct answer is B.

Question 13

1 / -0

Use the following information to answer the next question.

Brahma rolls down a ball from a certain height along an inclined plane. After reaching the bottom of the inclined plane, the ball rolls some distance horizontally along a surface. Brahma uses four different objects as the horizontal surface at the bottom of the inclined plane. The four objects are frosted glass sheet, cardboard sheet, sand paper, and wrinkle-free towel. In each case, he measures the distance travelled by the ball from the bottom of the inclined plane along the horizontal surface.

On which surface will the ball move the least distance?

Sand paper

Cardboard sheet

Frosted glass sheet

Wrinkle-free towel

Solution

Among the given surfaces, the towel offers the greatest frictional resistance to the rolling of the ball over it. A towel is made up of cotton threads that offer a great amount of resistance, i.e., frictional force, to any motion over their surface. As the ball rolls down and moves on the towel, it stops quickly after travelling the shortest distance. This is because the friction offered by the towel surface to the moving ball is the greatest among the given surfaces.

The correct answer is D.

Question 14

1 / -0

Use the following information to answer the next question.

Four cubical boxes, made up of the same material, are placed on the ground and are pushed with a constant force. d₁, d₂, d₃, and d₄ are the distances travelled by the boxes. They are related as d₃ > d₂ > d₄ > d₁.

The sides a₁, a₂, a₃, and a₄ of the respective boxes are related as

a₁ > a₂ > a₃ > a₄

a₁ > a₄ > a₂ > a₃

a₃ > a₂ > a₄ > a₁

a₄ > a₃ > a₂ > a₁

Solution

The motion of the boxes on the ground is opposed by the friction offered by the irregularities present on the surface. The magnitude of friction depends on the mass of the moving object. The greater the mass of the moving object, the more is the friction and vice-versa. Here all the boxes are cubical in shape and made up of the same material. Therefore, the friction of each box will depend on its volume, which is proportional to its mass.

It is given that the distances are related as d₃ > d₂ > d₄ > d₁.

Hence, it can be inferred that the frictions offered by the ground to the boxes are related as:

Friction on box 1 > Friction on box 4 > Friction on box 2 > Friction on box 3

Hence, the masses, i.e., the volumes in this case are related as:

Mass of box 1 > Mass of box 4 > Mass of box 2 > Mass of box 3

Therefore, the sides of the boxes are related as: a₁ > a₄ > a₂ > a₃

The correct answer is B.

Question 15
1 / -0

Use the following information to answer the next question.

There are three types of friction, namely sliding, static, and rolling. They are respectively denoted as f_sl, f_st, and f_roll.

On a given surface, the given frictional forces are related as

A
f_sl> f_st> f_roll

B
f_st> f_sl> f_roll

C
f_st> f_roll> f_sl

D
f_sl> f_roll> f_st

Solution

The force of friction present between any two given objects depends on the nature of the motion of one over the other. Friction is offered by the interlocking of surfaces. When two surfaces are at rest over one another, the interlocking is the maximum. This is called static friction. Maximum force is required to overcome static friction (f_st). Sliding friction, f_sl, is greater than rolling friction, f_roll. This is because it is more difficult to slide over interlockings than roll them over. Hence, these frictions are related as:

f_st> f_sl> f_roll

The correct answer is B.

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Friction Test - 11

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Friction Test - 11

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Question 1

Fc < Fm < Fs

Fc < Fs < Fm

Fm < Fc < Fs

Fs < Fc < Fm

Solution

Question 2

oil magnifies the applied muscular force

oil reduces the friction between two surfaces

application of oil generates an upward thrust

application of oil reduces the gravitational force

Solution

Question 3

II

III

IV

V

Solution

Question 4

speak and listen

write and walk

speak and walk

write and listen

Solution

Question 5

reduce friction

develop more heat

increase gravitational force

change atmospheric pressure

Solution

Question 6

hold them easily

reduce their cost

make them strong

increase their friction

Solution

Question 7

sliding friction is greater than rolling friction

rolling friction is greater than sliding friction

static friction is greater than sliding friction

sliding friction is greater than static friction

Solution

Question 8

Threading tires

Grinding on stones

Making spikes on shoes

Powdering a carom board

Solution

Question 9

Temperature

Pressure

Friction

Density

Solution

Question 10

only I is correct

only III is correct

both I and II are correct

both II and III are correct

Solution

Question 11

static friction

rolling friction

sliding friction

kinetic friction

Solution

Question 12

I

II

III

IV

Solution

F_c < F_m < F_s

F_c < F_s < F_m

F_m < F_c < F_s

F_s < F_c < F_m

a₁ > a₂ > a₃ > a₄

a₁ > a₄ > a₂ > a₃

a₃ > a₂ > a₄ > a₁

a₄ > a₃ > a₂ > a₁

f_sl> f_st> f_roll

f_st> f_sl> f_roll

f_st> f_roll> f_sl

f_sl> f_roll> f_st