AP 8th Class Physical Science Bits Chapter 2 Friction with Answers

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AP State Syllabus 8th Class Physical Science Bits 2nd Lesson Friction with Answers

Choose the correct answer.

Question 1.
The frictional force exerted by fluids is called
A) rolling friction
B) sliding friction
C) drag
D) normal force
Answer:
C) drag

Question 2.
The unit of force is
A) metre
B) km
C) kilogram-weight
D) joule
Answer:
C) kilogram-weight

Question 3.
Friction is proportional to
A) normal force
B) force
C) mass
D) none of these
Answer:
A) normal force

Question 4.
………… reduce the frictions.
A) Lubricants
B) Drag
C) Mass
D) None of these
Answer:
A) Lubricants

Question 5.
The change in the length of a spring is …………. to the applied force.
A) Indirect proportional
B) Equal
C) Direct proportional
D) Not depends on the force
Answer:
C) Direct proportional

Question 6.
When the speed of the body moving in a straight line changes continuously then the body acquires
A) Acceleration
B) Speed
C) Velocity
D) Displacement
Answer:
A) Acceleration

Question 7.
The bodies of birds and Ashes must have evolved to shapes which would make them not to loose much energy in overcoming …………. friction.
A) Rolling friction
B) Static friction
C) Sliding friction
D) Fluid friction
Answer:
D) Fluid friction

Question 8.
Which of the following friction has self adjusting force?
A) Sliding friction
B) Static friction
C) Rolling friction
D) Fluid friction
Answer:
B) Static friction

Question 9.
Friction is independent of
A) Nature of surface
B) Normal force
C) Irregularities in surface
D) Area of contact
Answer:
D) Area of contact

Question 10.
To overcome friction …………… are used in machinery.
A) dynamo
B) motor
C) wires
D) ball bearings
Answer:
D) ball bearings

Question 11.
Friction produces
A) light
B)sound
C) heat
D) none of these
Answer:
C) heat

Question 12.
The friction exerted by moving body is called
A) static friction
B) sliding friction
C) rolling friction
D) drag
Answer:
B) sliding friction

Question 13.
The friction acting on the body which is at rest is
A) sliding friction
B) static friction
C) rolling friction
D) drag
Answer:
B) static friction

Question 14.
The friction exerted by fluid is called
A) static friction
B) sliding friction
C) rolling friction
D) drag
Answer:
C) rolling friction

Question 15.
The friction which is least among all the frictions
A) static friction
B) sliding friction
C) rolling friction
D) drag
Answer:
C) rolling friction

Question 16.
The force which opposes the relative motion of two surfaces of the bodies which are in contact is called
A) muscular force
B) frictional force
C) gravitational force
D) magnetic force
Answer:
B) frictional force

Question 17.
…………. friction is self adjusting force.
A) Static
B) Sliding
C) Rolling
D) Both A & B
Answer:
A) Static

Question 18.
When applied force is …………… than the limit of the static friction than the body starts to move. ( )
A) less
B) more
C) equal
D) none of these
Answer:
B) more

Question 19.
Friction is caused by the ………….. on the two surfaces which are in contact, i) smoothness ii) irregularities
iii) roughness iv) cleanliness
A) i and iv
B) ii and iii
C) iii and iv
D) all the above
Answer:
B) ii and iii

Question 20.
Because of friction …………. of surfaces increases.
A) density
B) volume
C) temperature
D) pressure
Answer:
C) temperature

Question 21.
When one body rolls over the surface of another body, the friction offered is called ………….
A) static friction
B) sliding friction
C) drag
D) rolling friction
Answer:
D) rolling friction

Question 22.
……………. and ……………. are called fluids.
A) Liquids, gases
B) Solids, liquids
C) Solids, gases
D) Solids, moltens
Answer:
A) Liquids, gases

Question 23.
The length of the spring is proportional to ………..
A) size of the spring
B) thickness of spring
C) volumed spring
D) the applied force
Answer:
D) the applied force

Question 24.
Choose suitable option for matching.
Group-A — Group-B
1. Static friction — a) Drag
2. Sliding friction — b) Object at rest
3. Rolling friction — c) Nature of surface
4. Fluid friction — d) Object in motion
5. Friction — e) Ball bearings
A) 1 – a, 2 – b, 3 – c, 4 – d, 5 – e
B) 1 – b, 2 – d, 3 – e, 4 – a, 5 – c
C) 1 – b, 2 – c, 3 – d, 4 – e, 5 – a
D) 1 – d, 2 – e, 3 – a, 4 – b, 5 – c
Answer:
B) 1 – b, 2 – d, 3 – e, 4 – a, 5 – c

Question 25.
Choose suitable option for matching.
Group – A — Group – B
1. Lubricants — a) Increases friction
2. Normal force — b) Friction is independent
3. Area of contact — c) Decreases the friction
4. Friction — d) To overcome fluid pressure
5. Shape of birds — e) Produces heat
A) 1 – c, 2 – a, 3 – b, 4 – e, 5 – d
B) 1 – a, 2 – b, 3 – c, 4 – d, 5 – e
C) 1 – b, 2 – c, 3 – d, 4 – e, 5 – a
D) 1 – d, 2 – e, 3 – a, 4 – b, 5 – c
Answer:
A) 1 – c, 2 – a, 3 – b, 4 – e, 5 – d

Question 26.
If we rub our hands, heat is generated by
A) static friction
B) sliding friction
C) rolling friction
D) drag
Answer:
B) sliding friction

Question 27.
a) When the surface of one objectmoves relative to the surface of another object, static friction exerts,
b) When surfaces of the objects are at rest, sliding friction exerts.
A) a is true
B) b is true
C) both a and b are true
D) both a and b are false
Answer:
D) both a and b are false

Question 28.
Assertion (A): The force of friction is greater if a rough surface is involved.
Reason (R): Rough surface contains a large number of irregularities.
A) A and R are true, R supports A
B) A and R are false
C) A and R are true, R does not support A
D) A is true, but R is false
Answer:
A) A and R are true, R supports A

Question 29.
The substances which reduce friction are called as
A) paints
B) lubricants
C) alloys
D) grippers
Answer:
B) lubricants

Question 30.
Friction is not depends upon
A) nature of surface
B) normal force
C) area of contact
D) A and B
Answer:
D) A and B

Question 31.
If there is no heat shield covering over the space craft shuttle, it will
A) fall
B) burn
C) escape
D) rotate
Answer:
B) burn

Question 32.
Opposite to acceleration is
A) deceleration
B) retardation
C) negative acceleration
D) all of these
Answer:
D) all of these

Question 33.
If you push a ball which is in the rest on a ground, then its speed
A) first increases, then decreases
B) first increases, then remains constant
C) first decreases, then increases
D) first decreases, then come to rest
Answer:
A) first increases, then decreases

Question 34.
If we increases weights, the direction of motion of block on the trolley is

A) towards left side
B) towards right side
C) upwards
D) downwards
Answer:
B) towards right side

Question 35.
In which of the following surface a ball move fastly?
A) Covered with grass
B) Covered with hard cement
C) Covered with sand
D) Covered with saw dust
Answer:
B) Covered with hard cement

Question 36.
If you increase normal force, then
A) friction force increases
B) friction force decreases
C) no change in the frictional force
D) we cannot say
Answer:
A) friction force increases

Question 37.
A push or a pull is called
A) force
B) friction
C) acceleration
D) velocity
Answer:
A) force

Question 38.
……………. is friction comes into play when surface of one object moves relative to the other surface of another object
A) Static friction
B) Sliding friction
C) Rolling friction
D) None of these
Answer:
B) Sliding friction

Question 39.
The friction which comes to play when surfaces of the objects are at rest relative to each other
A) static friction
B) sliding friction
C) rolling friction
D) none of these
Answer:
A) static friction

Question 40.
In the given below frictions, which friction is self adjusting force?
A) sliding friction
B) static friction
C) rolling friction
D) fluid friction
Answer:
B) static friction

Question 41.
Adjacent experiment represents

A) Understanding the nature of friction and the concept of static friction
B) Observing variation of friction
C) Effect of area of contact of frictional area
D) None of the above
Answer:
A) Understanding the nature of friction and the concept of static friction

Question 42.
Adjacent activity is example for

A) Produce of heat by friction
B) Reduce of friction
C) Effect of rollers of friction
D) None
Answer:
A) Produce of heat by friction

Question 43.
Adjacent activity represents

A) Produce of heat by friction
B) Reduce of friction
C) Effect of rollers of friction
D) Observing fluid friction
Answer:
D) Observing fluid friction

Question 44.
Push a heavy box with a small force. It does not move. Now gradually increase the force, the box till does not move. From this experiment your conclusion is
A) force increases, friction increases
B) force increases, friction decreases
C) force increases, no change in friction
D) none of the above
Answer:
A) force increases, friction increases

Question 45.
From this experiment the conclusion is

A) Friction force at ‘a’ > friction force at ’b’
B) Friction force at ’a’ < friction force at ‘b’
C) Friction force at a’ = friction force at ‘b’
D) None of the above
Answer: C) Friction force at a’ = friction force at ‘b’

Question 46.
To prove that the frictional force is independent of the area of contact, the required materials and apparatus are
A) weighing machine, brick, thread
B) spring balance, brick, thread
C) spring balances
D) inclined plane, spring balance
Answer:
B) spring balance, brick, thread

Question 47.
Pull one brick with a spring balance (Reading – 1)
Pull two bricks with a spring balance (Reading – 2) A) 1 > 2
B) 2 > 1
C) 1 = 2
D) 2 >1
Answer:
B) 2 > 1

Question 48.
How do you prove that friction produces heat?
A) By rubbing your palms against each other
B) By striking a match stick against a rough surface
C) By putting iron rod in the sunlight
D) A or B
Answer:
B) By striking a match stick against a rough surface

Question 49.
Which of the following is wrong statement?
A) Friction is reduceble
B) Static friction gives movement to a body
C) Solids do not exert drag
D) Above all
Answer:
B) Static friction gives movement to a body

Question 50.
This figure indicates free body diagram

A) a moving car
B) a car in a rest
C) A or B
D) A monkey hanging to a branch of tree
Answer:
C) A or B

Question 51.

Drag is not observed in
A) a
B) b
C) c
D) d
Answer:
D) d

Question 52.

From the above data match the following.
a) static friction
b) rolling friction
c) sliding friction
A) A-b, B-c, C-a
B) A-c, B-b, C-a
C) A-a, B-b, C-c
D) A-b, B-a, C-c
Answer:
A) A-b, B-c, C-a

Question 53.
The change in the length of the spring is ………… to the applied force.
A) indirect proportional
B) equal
C) direct proportional
D) not depends on the force
Answer:
C) direct proportional

Question 54.
Adjacent figure represents

A) pushing a heavy box
B) rubbing a box
C) opening a box
D) friction of a box
Answer:
A) pushing a heavy box

Question 55.
Which of the following diagram indicates rolling friction?

Answer:
A)

Question 56.
The wrong in diagram is

A) F
B) W
C) f
D) f and W
Answer:
D) f and W

Question 57.
Directions of ‘a’, ‘b’ refers as

A) weight (a), friction (b)
B) friction (a), weight (b)
C) friction (b), movement (a)
D) movement (a), friction (b)
Answer:
D) movement (a), friction (b)

Question 58.
Friction is said to be a Mend, because it helps
A) to walk on a road
B) to hear a sound
C) to sea a book
D) to think a problem
Answer:
A) to walk on a road

Question 59.
Which of the following play major role to avoid corrosion due to Motion?
A) Paints
B) Lubricants
C) Alloys
D) Galvanizing
Answer:
B) Lubricants

Question 60.
“Don’t throw over the roads, they may cause slip” is applicable to
A) bananas
B) oils
C) sand
D) above all
Answer:
D) above all

Question 61.
This gives to birds and fishes to overcome from drag.
A) Colour of the body
B) Shape of the body
C) Mass of the body
D) Above all
Answer:
B) Shape of the body

Question 62.
Which of the following is correct?
A) Friction is good
B) Friction is evil
C) Both
D) None
Answer:
C) Both

Question 63.
The Mction exerted by a rolling body is
A) static friction
B) sliding friction
C) rolling friction
D) none of these
Answer:
C) rolling friction

Question 64.
………… is responsible for over heating and wearing out of moving parts.
A) Normal force
B) Friction
C) Tension
D) Gravitational force
Answer:
B) Friction

Question 65.
Gymnasts apply which material on their hands to increase Motion for better grip?
A) oil
B) soaps
C) coarse substance
D) water
Answer:
C) coarse substance

Question 66.
Which of the following is easy to push?
A) A brick in horizontal position
B) A brick in vertical position
C) Both are equal to push
D) We cannot say
Answer:
C) Both are equal to push

Question 67.
In railway station, Ranga put one box in his head and Ramu put two boxes in his head of same weight.
The normal force exerts more on
A) Ranga
B) Ramu
C) Both are equal
D) No normal force acts on them
Answer:
B) Ramu

Question 68.
It is difficulty to walk on slippery surfaces, because there exists
A) less friction
B) more friction
C) less area of surface
D) more area of surface
Answer:
A) less friction

Question 69.
Which of the given daily activity linked with Mctional force?
A) Fin a nail into the wall
B) Apply brakes to stop a vehicle
C) Hold a pencil to write
D) Above all
Answer:
D) Above all

Question 70.
Which of the above linked with less Motion?

A) a, d
B) a, b, c
C) d
D) None
Answer:
C) d

Question 71.
More friction requires in the given systems.
A) Tyres of vehicles and road
B) Machinery wheels
C) Pen and hand
D) Above all
Answer:
D) Above all

Question 72.
In this games/sports less Motion is required
A) pole jump
B) carrom board
C) running
D) wrestling
Answer:
B) carrom board

Question 73.
More rough surfaces are observed in
A) bottom of the shoe
B) pattern of the tyre
C) foot path
D) above all
Answer:
D) above all

Question 74.
Ravi observed holes in a flexi banners.
They prevents
A) drag friction
B) static friction
C) sliding friction
D) rolling friction
Answer:
A) drag friction

Question 75.

The body is not moving, then the Motion is
A) 30 N (→)
B) 30 N (←)
C) 50 N (→)
D) 50 N(←)
Answer:
A) 30 N (→)

Question 76.
Portars use Thalapaga (bundle of cloth) (turban) on their heads while carrying luggage this provides
A) more friction
B) less friction
C) more pressure
D) less pressure
Answer:
D) less pressure

Question 77.
To reduce Motion between rotating shafts of machine tools, we use
A) Carbon powder
B) Sand
C) Powder
D) Ball bearings
Answer:
D) Ball bearings

Question 78.
Which of the following ways to reduce Mction in daily life?
A) Using lubricants
B) Using ball bearing
C) Polishing the planes
D) All the above
Answer:
D) All the above

Question 79.
The purpose of Powder while playing carroms is
A) to decrease friction
B) to increase friction
C) either to decrease or to increase of friction
D) keep the friction as constant
Answer:
A) to decrease friction

Question 80.
Situations:
i. Flying bird in the air
ii. Swimming fish in the water
iii. Moving aeroplane in the sky
Which of the above feels fluid friction?
A) only (i)
B) only (ii)
C) only (i) and (ii)
D) (i), (ii) and (iii)
Answer:
D) (i), (ii) and (iii)

Question 81.
Ganesh is cycling. After moving some distance he suddenly stopped cycling. Then bicycle gradually slowed down and Anally come to rest. Now predict the reason behind that
i) Frictional force between earth and wheels of the bicycle
ii) Frictional force between Air and bicycle
iii) Frictional force between bicycle and Ganesh
A) ii and iii only True
B) i and iii only True
C) i, ii and iii are True
D) i and ii only True
Answer:
D) i and ii only True

Question 82.
Assertion (A): A ball is moving fast on smooth surface than rough surface even you apply same force on it.
Reason (R): Force of friction is greater on a rough surface.
A) Both Assertion and Reason are correct and “R” is wrong explanation for “A”.
B) Assertion is correct and Reason is incorrect.
C) Both Assertion and Reasons are wrong.
D) Both Assertion and Reasons are correct and “R” is correct explanation for Assertion.
Answer:
D) Both Assertion and Reasons are correct and “R” is correct explanation for Assertion.

Question 83.
Assertion (A): Rollers are fitted to suitcase to pull easily.
Reason (R): It is always difficult to roll a body than to slide it over a surface.
A) Both Assertion and Reason are correct and Reason is wrong explanation.
B) Assertion is correct, Reason is incorrect.
C) Both Assertion and Reasons are incorrect.
D) Both Assertion and Reasons are correct and Reason is correct explanation.
Answer:
B) Assertion is correct, Reason is incorrect.

Question 84.
Why are Aeroplanes constructed as shown in figure?

A) To overcome fluid friction
B) To overcome rolling friction
C) To overcome static friction
D) To overcome sliding friction
Answer:
A) To overcome fluid friction

Question 85.
Which experiment do you perform on friction from the following equipments? Trolley, Weights, Weight hangers, Pulley, Inextensible string and table.
A) Friction is proportional to the normal force
B) To understand nature of friction and the concept of static friction
C) Effect of roughness on frictional force
D) Frictional force is independent of the area of contact
Answer:
B) To understand nature of friction and the concept of static friction

Question 86.
You wanted to know effect of roughness on frictional force. Which of the following material is not needed for your experiment?
A) Inclined plane
B) Rough cloth
C) Stop watch
D) Ball
Answer:
C) Stop watch

Question 87.
Frictional force on a object in a fluid depends on
A) Shape of the object
B) Nature of the fluid
C) All of the above
D) Speed with respect to fluid
Answer:
C) All of the above

Question 88.
“Aravind observed that heat is produced when he rubbed his palms.” The type of friction of acting here is
A) Static friction
B) Rolling friction
C) Fluid friction
D) Sliding friction
Answer:
D) Sliding friction

Question 89.
Which of the following is incorrect in the case of friction?
A) Frictional force is dependent of the area of contact.
B) Friction is proportional to the normal force.
C) Friction opposes the relative motion between two surfaces in contact.
D) Friction opposes the motion of a body.
Answer:
A) Frictional force is dependent of the area of contact.

Question 90.
“To reduce the friction we use solid, liquid and Gaseous state lubricants”. Which lubricant is used in Electric motor to reduce friction ?
A) Ball – bearing
B) Powder
C) All of the above
D) Grease
Answer:
D) Grease

Question 91.
Why are you appreciating Heat shield?
A) Heat shield can turn space craft attractively
B) Heat shield can make space craft light weight.
C) Heat shield reduces speed of the space craft.
D) Heat shield reduces heat produced by friction
Answer:
D) Heat shield reduces heat produced by friction

(92 – 93) Irregularities on the surfaces lock into one another when we attempt to move on any surface. We have to apply a force to over come interlocking. On rough surfaces in which a large number of irregularities exist. So the force of friction is greater if a rough surface is involved.
Question 92.
Above information tells us about ………..
A) Pressure
B) Friction
C) Time
D) Mass
Answer:
B) Friction

Question 93.
What would you generalise from the above information?
A) Friction decreases with increasing roughness
B) Friction is independent of Roughness
C) All surfaces have same friction
D) Friction increases with increasing roughness
Answer:
D) Friction increases with increasing roughness

Question 94.
Uma: Friction depends on the nature of the surface.
Usha: Friction is independent of area of contact,
A) Uma is correct, Usha is incorrect
B) Uma is incorrect, Usha is correct
C) Both Uma and Usha are correct
D) Both Uma and Usha are incorrect
Answer:
C) Both Uma and Usha are correct

Question 95.
A boy slides a marble, coin, matchbox and eraser. Which of the following objects moves dead slowly on the inclined plane?
A) Marble
B) Coin
C) Matchbox
D) Eraser
Answer:
C) Matchbox

Question 96.
In what direction does frictional force act when a body moves on the surface of another body?
A) In the direction of motion
B) In the direction opposite to motion
C) Perpendicular to direction of motion
D) Frictional force does not have direction
Answer:
B) In the direction opposite to motion

Question 97.
The fish swim easily in water because by
A) More energy
B) Streamlined shape
C) Both (A) and (B)
D) None of the above
Answer:
B) Streamlined shape

Question 98.
Hypothesis: The sole of shoe’s grave is to provide better grip on the floor.
Reason: Friction is caused by the irregularities on the two surface those are in contact.
A) Hypothesis is correct. Reason is correct explanation of hypothesis.
B) Hypothesis is correct. Reason is not correct explanation of hypothesis
C) Hypothesis is not correct and reasons are correct
D) Both hypothesis and reasons are not correct
Answer:
A) Hypothesis is correct. Reason is correct explanation of hypothesis.

Question 99.
A car toy is dropped on four inclined planes made up of with different materials. On which incline plane the car travels more distance?
A) Cemented surface
B) Mud surface
C) Marble surface
D) Brick surface
Answer:
C) Marble surface

Question 100.
It is difficult to walk on polished floor because friction between our feet and floor is
A) Increased
B) Reduced
C) Same
D) None of these
Answer:
B) Reduced

Question 101.
Toy car released with the same initial speed will travel farthest on
A) Muddy surface
B) Polished marble surface
C) Cemented surface
D) Brick surface
Answer:
B) Polished marble surface

Question 102.
Friction occurs due to?
A) Smoothness of the surfaces in contact
B) The gravitation force exerted by Earth on surfaces
C) Irregularities of the surfaces in contact
D) The attraction between charged bodies in contact
Answer:
C) Irregularities of the surfaces in contact

Question 103.
Relative to the surface, the direction of the friction is always
A) In the direction of motion of the object
B) Opposite to direction of the motion of the object
C) Perpendicular to direction of the motion of the object
D) No relation between direction of the motion and friction
Answer:
B) Opposite to direction of the motion of the object

Question 104.
Which of the following represents the correct sequence of types of friction arranged on based on their strength or magnitude?
A) Static friction < sliding friction < rolling friction
B) Rolling friction < sliding friction < static friction
C) Sliding friction < rolling friction < static friction
D) Rolling friction < static friction < sliding friction
Answer:
B) Rolling friction < sliding friction < static friction

Question 105.
Friction is independent of
A) Area of contact
B) Nature of the surface
C) Nature of the body
D) All of the above
Answer:
A) Area of contact