PHYSICS

BOOKS - NCERT FINGERTIPS PHYSICS

(HINGLISH)

LAWS OF MOTION

The Law Of Inertia

1. The term inertia was first used by

A. Newton
 B. Galileo

C. Aristotle

D. Kepler

Answer: B

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2. lnertia is that property of a body by virtue of

which the body is

A. unable to change by itself the state of rest

 B. unable to change by itself the state of

uniform motion.

C. unable to change by itself the direction of

motion.

D. unable to change by itself the state of rest or

of uniform motion

Answer: D

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3. A passenger getting down from a moving bus,

falls in the direction of the motion of the bus. This

is is an example for

A. second law of motion

B. second law of motion

C. second law of motion

D. inertia of motion

Answer: D

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4. A ball is travelling with uniform translatory

motion . This means that

A. it is at rest.

B. the path can be a straight line or circular and

the ball travels with uniform speed.

C. all parts of the ball have the same velocity

(magnitude and direction) and the velocity is

constant.

D. the centre of the ball moves with constant

velocity and the ball spins about its centre

uniformly.
Answer: C

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5. When a speeding bus stop suddenly, passengers

are thrown forward from their seats because

A. the back of seat suddenly pushes the

passengers forward.

B. inertia of rest stops the bus and takes that

body forward.
 C. upper part of that body continuous to be

state of motion whereas that the lower part

of the body in contact with seat remains rest.

D. upper part of the body come to rest whereas

the lower part of the body in contact with

seat begins to move.

Answer: C

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Conservation Of Momentum
1. Which one of the following statements is not true

A. The same force for the same time causes the

same change in momentent for different

bodies.

B. The rate of change of momentum of a body is

directly proportional to the applied force and

takes place in the direction in which the force

acts.

C. A greater opposing force is needed to stop a

heavy body than a light body in the same

time, if they are moving with the same speed.

 D. The greater the change in the momentum in a

given time, is the forece that needs to be

applied.

Answer: D

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2. A shell of mass 200g is fired by a gun of mass

100kg. If the muzzle speed of the shell is 80ms

−1
,

then the rcoil speed of the gun is

A. 16cms −1
 B. 8cms −1

C. 8ms −1

D. 16ms −1

Answer: A

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3. a 100kg gun fires a ball of 1kg horizontally from a

cliff of height 500m. If falls on the ground at a

distance of 400m from the bottom of the cliff. The

recoil velocity of the gun is (Take g: 10ms −2

 A. 0.2ms −1

B. 0.4ms −1

C. 0.6ms −1

D. 0.8ms −1

Answer: B

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4. A riding ball of mass m strikes a rigid wall at 60

∘

and gets reflected without loss of speed as shown

in the figure below. The value of impulse imparted

by the wall on the ball will be.

A. Mv
 B. 2mV

mV
C.
2

mV
D.
3

Answer: A

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Equilibrium Of A Particle

1. A body subjected to three concurrent force is

found to be in equilibrium. The resultant of any two

force
 A. is equal to third force

B. is equal to third force

C. is collinear fifth the third force

D. all of these

Answer: D

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2. Three concurrent co-planer force 1N , 2N and 3N

acting along different directions on a body

 A. can keep the body in equilibrium if 2 N and J N

act at right angle.

B. can keep the body in equilibrium if I N and 2 N

act at right angle.

C. cannot keep the body in equilibrium.

D. cannot keep the body in equilibrium.

Answer: C

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3. There are four force acting at a point p produced

by strings as shown in figure, which is at rest. The

force F and F are .

1 2

1 3
A. N, N
√2 √2

3 1
B. N, N
√2 √2

1 1
C. N, N
√2 √2
 3 3
D. N, N,
√2 √2

Answer: A

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4. A body of mass 10kg is acted upon by two per

pendicular forces 6N and 8N . The resultant ac-

celeration of the body is .

A.

−1
3
−2
1ms at angle of tan ( )w. r. t. 8N force
4
 B.

−1
3
−2
0.2ms at angle of tan ( )w. r. t. 8N force
4

C.

−2 −1
4
1ms at angle of tan ( )w. r. t. 8N force
3

D.

−2 −1
4
0.2ms at angle of tan ( )w. r. t. 8N force
3

Answer: A

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5. A body is moving under the action of two force
−−−−−−−−−−→ −−−−−−−−−−→

F1 = 2 î − 5 ĵ , F2 = 3 î − 4 ĵ . Its velocity will

−
→
become uniform under a third force F given by. 3

A. 5 î − ĵ

B. − 5 î − ĵ

C. 5 î + ĵ

D. − 5 î + 9 ĵ

Answer: D

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6. A block fof mass 5kg is suspended by a massless

rope of length 2 m from the ceilling. A force of 50

N is applied in the horizontal direction at the

midpoint P of the rope, as shown in the figure. The

angle made by the rope with the vertical in

equilibrium is (Take g = 10ms
−2
m .

A. 30 ∘

B. 40 ∘

C. 60 ∘
 D. 45 ∘

Answer: D

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Common Forces In Mechanics

1. Which of the following statements is correct

about friction?

A. The coefficient of friction between a given pair

of substances is largely independent of the

 area of contact between them.

B. The frictional force can never exceed the

reaction force on the body from the support

surface.

C. Rolling friction is only slightly smaller than

slidmg friction.

D. The main source of friction is the irregularity

of the surfaces in contact.

Answer: A

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2. Identify the correct statement.

A. Static friction depends on the area of contact.

B. Kinetic friction depends on the area of

contact.

C. Coefficient of static formation does not

depend on the surfaces in contact.

D. Coefficient of kinetic friction is less than the

coefficient of static friciton.

Answer: D

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3. Which of the following is a self adjusting force ?

A. Static friction

B. Rolling friction

C. Sliding friction

D. Dynamic friction

Answer: A

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4. Which one of the following can also act as a

lubricant in the machines?

A. Iron fillings

B. Polish on machines

C. Flow of waler through the machine

D. Flow of compressed and purifie air.

Answer: D

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5. A girl press her physics text book against a rough

vertical wall with her hand. The direction of the

frictional force on the book exerted by the wall is

A. downwards

B. upwards

C. out from the wall

D. into the wall

Answer: B

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6. A car accelerates on a horizontal road due to the

force exerted by

A. the engine of the car

B. the driver of the car

C. the car on earth

D. the road on the car

Answer: D

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7. A block of mass m rests on a rough inclined plane.

The coefficient of friction between the surface and

the block is µ. At what angle of inclination θ of the

plane to the horizontal will the block just start to

slide down the plane?

A. θ = tan
−1
μ

B. θ = cos
−1
μ

C. θ = sin
−1
μ

D. θ = sec
−1
μ

Answer: A

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8. When a body slides down from rest along a

smooth inclined plane making an angle of 30 with

∘

the horizontal, it takes time 20s. When the same

body slides down from rest along a rough inclined

plane making the same angle and through the same

distance, it takes time 20p is, where p is some

number greater than 1. The coefficient of friction

between the body and the rough plane is

1 1
A. μ = (1 − )
2
p √3

1
B. μ = (1 −
2
)
9p

1
C. μ 2
= (1 − p )
√3
 D. μ = √1 − 9p
2

Answer: A

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9. The minimum force required to start pushing a

body up a rough (frictional coefficient ) inclined

μ

plane is F1 while the minimum force needed to

prevent it from sliding down is F2 . If the inclined

plane makes an angle θ with the horizontal such

F1
that tan θ = 2μ then the ratio is .
F2

A. 4
 B. 1

C. 2

D. 3

Answer: D

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10. A block of mass 10kg is placed on a rough

horizontal surface having coefficient of friction

μ = 0.5 . If a horizontal force of 100N is acting on

it, then acceleration of the block will be.

 A. 10ms −2

B. 5ms −2

C. 15ms −2

D. 0.5ms −2

Answer: B

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11. The coefficient of static friction between the box

and the train's floor is 0.2. The maximum

acceleration of the train in which a box lying on its

floor will remain stationary is (Take g = 10ms

−2
)
 A. 2ms −2

B. 4ms −2

C. 6ms −2

D. 8ms −2

Answer: A

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12. A block of mass 1 kg lies on a horizontal surface

in a truck. The coefficient of static friction between

the block and the surface is 0.6. If the acceleration

of the truck is 5m / s
2
, the frictional force acting on

the block is…………newtons.

A. 10N

B. 5N

C. 2.5N

D. 20N

Answer: B

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13. A block of mass 2kg rests on a rough inclined

plane making an angle of 30

∘
with the horizontal.

The coefficient of static friction between the block

and the plane is 0.7. The frictional force on the block

is

A. 10.3N

B. 23.8N

C. 11.9N

D. 6.3N

Answer: C

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14. A block of mass M is held against a rough

vertical wall by pressing it with a finger . If the

coefficient of friction between the block and the

wall is μ and the acceleration due to gravity is g ,

calculate the minimum force required to be applied

by the finger to hold the block against the wall.

A. μM g

B. Mg

Mg
C.
μ

D. 2μM g
Answer: C

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15. A trolley of mass 20 kg is attached to a block of

mass 4kg by massless string passing over a

frictionless pulley as shown in the figure. If the

coefficient of kinetic friction between trolley and

the surface is 0.02, then the acceleration of the

trolley and block system is (T akeg = 10ms
−2
)

A. 1ms −2

B. 2ms −2

C. 1.5ms −2

D. 2.5ms −2

Answer: C

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16. In the question number 66, the tension in the

string is

A. 30N

B. 36N

C. 34N

D. 32N

Answer: C

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17. The rear side of a truck is open A box of 40kg

mass is placed 5m away from the open end as

shown in The coefficient of friction between the box

and the surface is 0.15. On a straight road, the truck

starts from rest and accelerating with 2m / s

2
. At

what dis tance from the starting point does the box

distance from the starting point does the box fall

from the truck? (Ignore the size of the box)

A. 20m
 B. 30m

C. 40m

D. 50m

Answer: A

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18. The coefficient of static friction between the two

blocks shown in figure is μ and the table is smooth.

What maximum horizontal forced F can be applied

to he block of mass M so that the block move

together?

A. 0.15mg

B. 0.05mg

C. 0.1mg

D. 0.45mg

Answer: D

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19. Two blocks A and B of masses 10 kg and 15 kg are

placed in contact with each other rest on a rough

horizontal surface as shown in the figure. The

coefficient of friction between the blocks and

surface is 0.2. A horizontal force of 200 N is applied

to block A. The acceleration of the system is

−2
(Take g = 10ms )

A. 4ms −2
 B. 6ms −2

C. 8ms −2

D. 10ms −2

Answer: B

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Circular Motion

1. A cyclist bends while taking turn to

A. reduce friction
 B. generate required centripetal force

C. reduce apparent weight

D. reduce speed

Answer: B

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2. A motor cyclist is going in a vertical circle what is

the necessary condition so that he may not fall

down ?

A. the force of gravity disappears.

 B. he loses weight some how.

C. he is kept in this path due to the force

exerted by surrounding air.

D. the frictional force of the wall balances his

weight

Answer: D

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3. One end of string of length l is connected to a

particle on mass m and the other end is connected

to a small peg on a smooth horizontal table. If the

particle moves in circle with speed v the net force

on the particle (directed toward centre) will be (T

reprents the tension in the string):

A. T
2
(mv)
B. T −
l

2
mv
C. T +
l

D. 0

Answer: A

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4. The mass of a bicycle rider along with the bicycle

is 100 kg. he wants to cross over a circular turn of

radius 100 m with a speed of 10ms

−1
. If the

coefficient of friction between the tyres and the

road is 0.6, will the rider be able to cross the turn?

Take g = 10ms
−2
.

A. 300N

B. 600N

C. 1200N

D. 150N

Answer: B
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5. A stone of mass m tied to the end of a string

revolves in a vertical circle of radius R. The net

forces at the lowest and highest points of the circle

directed vertically downwards are: [Choose the

correct alternative] Lowest point Highest point

T1 and V1 denote the tension and speed at the

lowest point T2 and V2 denote the corresponding

values at the highest points.

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6. A small objective placed on a rotating horizontal

turn table just slips when it is placed at a distance

4cm from the axis of rotation. If the angular velocity

of the trun-table doubled, the objective slip when

its distance from the axis of ratation is.

A. 1cm

B. 2cm

C. 4cm

D. 8cm

Answer: A

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7. A particle is moving on a circular path of 10 m

radius. At any instant of time, its speed is 5ms

−1

and the speed is increasing at a rate of 2ms

−2
. At

this instant, the magnitude of the net acceleration

will be

A. 5ms −2

B. 2ms −2

C. 3.2ms −2

D. 4.3ms −2

Answer: C
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8. In the question number 77, the force acting 011

thr particle is

A. mω 2
→r

B. − mω 2
→r

C. 2mω 2
→r

D. − 2mω 2
→r

Answer: B

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9. The coefficient of friction between the tyres and

the road is 0.1. The maximum speed with which a

cyclist can take a circular turn of radius 3 m without

skidding is (Take g = 10ms

−2
)

A. √15ms −1

B. √3ms −1

C. √30ms −1

D. √10ms −1

Answer: B

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10. A stone of mass 5 kg is tied to a string of length

10 m is whirled round in a horizontal circle. What is

the maximum speed with which the stone can be

whirled around if the string can withstand a

maximum tension of 200 N?

A. 10ms −1

B. 15ms −1

C. 20ms −1

D. 25ms −1

Answer: C

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 1
11. A disc revovles with a speed of 33 rev / min
3

and has a radius of 15 cm Two coins A and B are

palaced at 4 cm and 14 cm away from the center of

the record If the coefficient of friction between the

coins and the record is 0.5 which of the coins will

revolve with the record ?

A. A

B. B

C. Both A and B

D. Neither A nor B
Answer: A

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12. A circular race track of radius 300 m is banked at

an angle of 15 If the coefficient of friction between

∘

the wheels of a race car and the road is 0.2. What is

the (a) optimum speed of the race car to avoid wear

and tear on its tyres , and (b) maximum permissible

speed to avoid slipping ?

A. 10√3ms −1

B. 9√10ms −1
 C. √10ms −1

D. 2√10ms −1

Answer: B

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13. In the question number 82, the maximum

permissible speed to avoid slipping is

A. 18.6ms −1

B. 28.6ms −1

C. 38.6ms −1
 D. 48.6ms −1

Answer: C

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14. An aircraft executes a horizontal loop at a speed

of 720kmh −1
, with its wings banked at 15
∘
What

is the radiue of the loop ?

A. 14.8km

B. 14.8m

C. 29.6km
 D. 29.6m

Answer: A

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Solving Problem In Mechanics

1. An iron block of sides 50cm × 8cm × 15cm has

to be pushed along the floor. The force required will

be minimum when the surface in contact with

ground is

A. 8cm × 15cm surface

B. 50cm × 15cm surface

C. 8cm × 50cm surface

D. force is same for all surface

Answer: D

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2. Figure shows a man of mass 55 kg standing

stationary with respect to a horizontal conveyor

belt that is accelerating with 1ms

−2
. The net force

acting on the man is

A. 35N

B. 45N

C. 55N

D. 65N

Answer: C

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3. A helicopter of mass 2000 kg rises with a vertical

acceleration of 15ms −2
. The total mass of the crew

and passengers is 500 kg. Give the magnitude and

direction of the (g = 10ms

−2
)

(a) Force on the floor of the helicopter by the crew

and passengers.

(b) action of the rotor of the helicopter on the

surrounding air.

(c ) force on the helicopter dur to the surrounding

air.

A. 1.25 × 10
5
, 3
,
N 6.25 × 10 N 6.25 × 10 N
2
 B. 1.25 × 10 8
, 9
,
N 6.25 × 10 N 6.25 × 10 N
2

C. 1.25 × 10 5
, 3
,
N 6.25 × 10 N 6.25 × 10 N
7

D. 1.25 × 10 4
, 4
,
N 6.25 × 10 N 6.25 × 10 N
4

Answer: D

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4. A person in an elevator accelerating upwards

with an acceleration of 2ms

−2
, tosses a coin

vertically upwards with a speed of 20ms

−1
. After

how much time will the coin fall back into his hand ?

(g = 10 ms −2
)
 5
A. s
3

3
B. s
10

10
C. s
3

3
D. s
5

Answer: C

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5. The person o( mass 50 kg slands on a weighing

scale on a lift. If the lift is ascending upwards with a

uniform acceleration of 9ms −2

, what would be the
reading of the weighting scale?

−2
(Take g = 10ms )

A. 50kg

B. 60kg

C. 96kg

D. 176kg

Answer: C

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6. Block A of weight 100N rests on a frictionless

inclined plane of slope angle 30 (Fig. 5.7). A flexible

∘

cord attached to A passes over a frictonless pulled

and is connected to block B of weight W . Find the

weight W for which the system in equilibrium.

A. 25N

B. 50N

C. 75N
 D. 100N

Answer: B

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7. Two blocks of masses 10 kg and 20 kg are

connected by a massless string and are placed on a

smooth horizontal surface as shown in the figure. If

a force F=600 N is applied to 10 kg block, then the

tension in the string is

 A. 100N

B. 200N

C. 300N

D. 400N

Answer: D

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8. In the question number 91, if a force Fis applied

to 20 kg block, then the tension in the string is

A. 100N
 B. 200N

C. 300N

D. 400N

Answer: B

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9. Two masses of 5 kg and 3 kg are suspended with

the help of massless inextensible strings as shown

in figure. The whole system is going upwards with

an acceleration of 2ms
−2
. The tensions T1 and T2
are respectively (Take g = 10ms
−2
)
 A. 96N, 36N

B. 36N,96N

C. 96N,96N

D. 36N,36N

Answer: A

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10. Two blocks each of mass M are resting on a

frictionless inclined plane as shown in fig then:

 A. The block A moves down the plane

B. The block B moves down the plane.

C. Both the blocks remain at rest

D. Both the blocks move down the plane.

Answer: A

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11. In the system shown in the figure, the

acceleration of 1 kg mass is

g
A. downwards
4
 g
B. downwards
2

g
C. upwards
2

g
D. upwards
4

Answer: C

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12. Two masses 8 kg and 12 kg are connected at the

two ends of a light in extensible string that passes

over a friction less pulley Find the acceleration of

the masses and tension in the string , when the

masses are released

g
A.
4

g
B.
5

g
C.
8

g
D.
6

Answer: B

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13. A monkey of mass 40 kg climbs on a massless

rope which can stand a maximum tension of 500 N.

In which of the following cases will the rope break?

 −2
(Take g = 10ms )

A. The monkey climbs up with an acceleration of

5ms
−2
.
 B. The monkey climbs down with an acceleration

of 5ms −2
.

C. The monkey climbs up with a uniform speed

5ms
−2
.

D. The monkey falls down, the rope freely under

gravity.

Answer: A

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14. A book is lying on the table. What is the angle

belween the action of the book on the table and the

reaction of the table on the book?

A. 0 ∘

B. 45 ∘

C. 90 ∘

D. 180 ∘

Answer: D

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15. Two blocks of masses of 40 kg and 30 kg are

connected by a weightless string passing over a

frictionless pulley as shown in the figure.

A. 0.7ms −2

B. 0.8ms −2

C. 0.6ms −2

D. 0.5ms −2
Answer: A

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16. A mass of 1 kg is suspended by means of a

thread. The system is (i) lifted up with an

acceleration of 4.9ms
−2
(ii) lowered with an

acceleration of 4.9ms −2
. The ratio of tension in the

first and second case is

A. 3 : 1

B. 1 : 2

C. 1 : 3
 D. 2 : 1

Answer: A

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Higher Order Thinking Skills

1. Two particles of mass m each are tied at the ends

of a light string of length 2a. The whole system is

kept on a frictionless horizontal surface with the

string held tight so that each mass is at a distance

a from the centre P (as shown in the figure). Now,

the mid-point of the string is pulled vertically

upwards with a small but constant force F. As a

result, the particles move towards each other on

the surface. The magnitude of acceleration, when

the separation between them becomes 2x, is

F a
A.
2m √ 2 2
a − x
 F x
B. −
2m √a 2 − x 2

F x
C.
2m a

F √a 2 − x 2
D.
2m x

Answer: B

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2. A block of mass m is on an inclined plane of angle

θ . The coefficient of friction between the block and

the plane is μ and . The block is held

tan θ > μ

stationary by applying a force P parallel to the

plane. The direction of force pointing up the plane

is taken to be positive. As P is varied from

P1 = mg(sin θ − μ cos θ) to

P2 = mg(sin θ + μ cos θ) , the frictional force f

versus P graph will look like

A.

B.

C.

D.
Answer: A

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3. When body slides down from rest along smooth

inclined plane making angle of 45

∘
with the

horizontal, it takes time T When the same body

slides down from rest along a rough inclined plane

making the same angle and through the same

distance it is seen to take time pT , where p is some

number greater that 1. Calculate the coefficient of

friction beween the body and the rough plane.

A. 1/P

B. μ 2
= (1 − 1 / p )

C. 1 / p 2

D. 2-p

Answer: B

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4. What is the maximum value of the force F such

that the block shown in the arrangement, does not

move?
 A. 20N

B. 10N

C. 12N

D. 15N

Answer: A

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5. A string of negligible mass going over a clamped

pulley of mass m supports a block of mass M as

shown in the figure. The force on the pulley by the

clamp is given by

A. √2M g
 B. √2mg

C. √(M
2 2
+ m) + m g

D. √(M
2 2
+ m) + M g

Answer: D

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6. Assuming all the surface to be frictionless. The

smaller block m is moving horizontally with

acceleration a and vertically downwards with

acceleration a. Then magnitude of net acceleration

of smaller block m with respect to ground

2√5mg
A.
(5m + M )

2mg
B.
(5m + M )

C. 7√5g

D. none of these

Answer: A

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7. A block of mass is placed on a surface with a
3
x
vertical cross section given by y = . If the
6

coefficient of friction is 0.5, the maximum height

above the ground at which the block can be placed

without slipping is:

A. 1/2m

1
B. m
6

C. 2 / 3

D. 1 / 3m

Answer: B

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8. A piece of wire is bent in the shape of a parabola

y = kx
2
(y-axis vertical) with a bead of mass m on

it. The bead can slide on the wire without friction. It

stays at the lowest point of the parabola when the

wire is at rest. The wire is now accelerated parallel

to the x-axis with a constant acceleration a. The

distance of the new equilibrium position of the

bead, where the bead can stay at rest with respect

to the wire, from the y-axis is:

A. a/gk

B. a/2gk
 C. 2a/gk

D. a/4gk

Answer: B

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Ncert Exemplar

1. A ball is travelling with uniform translatory

motion . This means that

A. it is at rest
 B. he path can be a straight line or circular and

the ball travels with uniform speed.

C. all parts of the ball have the same velocity

(magnitude and direction) and the velocity is

constant

D. the centre of the ball moves with constant

velocity and the ball spins about its centre

uniformly.

Answer: C

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2. A metre scale is moving with uniform velocity.

This implies .

A. the force acting on the scale is zero, but a

torque about the centre of mass can act on

the scale.

B. he force acting on the scale is zero and the

torque acting about centre of mass of the

scale is also zero.

C. the total force acting on it need not be zero

but the torque on it is zero.

 D. neither the force nor the torque need to be

zero.

Answer: B

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3. A cricket ball of mass 150 g has an initial velocity

ū = (3 î − 4 ĵ)ms
−1
and a final velocity

v̄ = − (3 î − 4 ĵ)ms
−1
after being hit. The

change in momentum (final momentum -initial

momentum) is (in kg ms −1
)

A. zero
 B. − (0.45 î + 0.6 ĵ)

C. − (0.9 î + 1.2 ĵ)

D. − 5( î + ĵ)

Answer: C

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4. In the previous problem 3 the magnitude of the

momentum transferred during the hit is .

A. zero

B. 0.75kgms −1
 C. 1.5kgms −1

D. 14kgms −1

Answer: C

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5. Conservation of momentum in a collision

between particles can be understood from

A. conservation of energy.

B. Newton's first law onl

C. Newton's second law only.

 D. both Newton's second and third law.

Answer: D

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6. A hockey player is moving northward and

suddenly turns westward with the same speed to

avoid an opponet. The force that acts on the player

is.

A. frictional force along westward.

B. muscle force along southward.

 C. frictional force along south-west.

D. muscle force along south-west.

Answer: C

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7. A body of mass 2kg travels according to the law

x(t) = pt + qt
2 3
+ rt where

p = 3ms
−1
, q = 4ms
−2
and r = 5ms
−3
. Find the

force acting on the body at t=2 sec.

A. 136N
 B. 134N

C. 158N

D. 98N

Answer: A

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8. A body with mass 5 kg is acted upon by a force

→
F = ( − 3 î + 4 ĵ)N . If its initial velocity at t =0 is

, the time at which it will just

→ −1
v = 6 î − 12 ĵms

have a velocity along the y-axis is :

 A. 0

B. 10s

C. 2s

D. 15s

Answer: B

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9. A car of mass m starts from rest and acquires a

velocity along east υ = υ î (υ > 0) in two seconds

Assuming the car moves with unifrom acceleration

the force exerted on the car is .

 mv
A. eastward and is exerted by the car
2

engine.

mv
B. eastward and is due to the friction on
2

the tyres exerted by the road.

mv
C. more than eastward exerted due to the 2
2

engine and overcomes the friction of the

road.

mv
D. exerted by the engine.
2

Answer: B

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Assertion And Reason

1. Assertion : An external force is required to keep a

body in motion.

Reason : If the net external force is zero, a body at

rest continues to remain at rest and a body in

motion continues to move with a uniform velocity.

A. If both assertion and reason are true and

reason is the correct explanation of assertion.

B. If both assertion and reason are true and

reason is the not correct explanation of

assertion.
 C. If assertion is true but reason is false

D. If both assertion and reason are false.

Answer: B

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2. Assertion: For applying the second law of motion,

there is no conceptual distinction between

inanimate and animate objects.

Reason: An animate object requires an external

force to acceleration.
 A. If both assertion and reason are true and

reason is the correct explanation of assertion.

B. If both assertion and reason are true and

reason is the not correct explanation of

assertion.

C. If assertion is true but reason is false

D. If both assertion and reason are false.

Answer: B

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3. Assertion: If a body is momentarily at rest, it

means that force or acceleration are necessarily

zero at that instant.

Reason: Force on a body at a given time is

determined by the direction of motin only.

A. If both assertion and reason are true and

reason is the correct explanation of assertion.

B. If both assertion and reason are true and

reason is the not correct explanation of

assertion.

C. If assertion is true but reason is false

 D. If both assertion and reason are false.

Answer: D

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4. Assertion: If external force on a body is zero, its

acceleration is zero.

Reason: This is the simple from of Newton's second

law of motion.

A. If both assertion and reason are true and

reason is the correct explanation of assertion.

 B. If both assertion and reason are true and

reason is the not correct explanation of

assertion.

C. If assertion is true but reason is false

D. If both assertion and reason are false.

Answer: C

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5. Assertion: There is no apprecible change in the

position of the body during the action of the

impulsive force.
Reason: In case of impulsive force the time of action

of the force is very short.

A. If both assertion and reason are true and

reason is the correct explanation of assertion.

B. If both assertion and reason are true and

reason is the not correct explanation of

assertion.

C. If assertion is true but reason is false

D. If both assertion and reason are false.

Answer: A

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6. Assertion:On a merry-go-around, all parts of our

body are subjected to an inward force.

Reason: We have a feeling of being pushed outward

the direction of impending motion.

A. If both assertion and reason are true and

reason is the correct explanation of assertion.

B. If both assertion and reason are true and

reason is the not correct explanation of

assertion.

C. If assertion is true but reason is false

 D. If both assertion and reason are false.

Answer: B

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7. Assertion : The moment after a stone is released

out of an accelerated train, there is no horizontal

force or acceleration on the stone.

Reason : Force on a body at a given time is

determined by the situation at the location of the

body at that time.

 A. If both assertion and reason are true and

reason is the correct explanation of assertion.

B. If both assertion and reason are true and

reason is the not correct explanation of

assertion.

C. If assertion is true but reason is false

D. If both assertion and reason are false.

Answer: A

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8. Assertion: Force on a body A by body B is equal

and opposite to the force on the body B by A .

Reason: Force in nature always occur between pairs

of bodies.

A. If both assertion and reason are true and

reason is the correct explanation of assertion.

B. If both assertion and reason are true and

reason is the not correct explanation of

assertion.

C. If assertion is true but reason is false

D. If both assertion and reason are false.

Answer: B

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9. Assertion: There is no cause-effect relation

between action and raction.

Reason: Action and reaction are not simultaneous

force.

A. If both assertion and reason are true and

reason is the correct explanation of assertion.

B. If both assertion and reason are true and

reason is the not correct explanation of

 assertion.

C. If assertion is true but reason is false

D. If both assertion and reason are false.

Answer: C

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10. Assertion: The terms action and reaction in the

third law of motion stand for simultaneous mutual

force between a pair of bodies.

Reason: In this conext action always precede or

cause reaction.
 A. If both assertion and reason are true and

reason is the correct explanation of assertion.

B. If both assertion and reason are true and

reason is the not correct explanation of

assertion.

C. If assertion is true but reason is false

D. If both assertion and reason are false.

Answer: C

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11. Assertion : The total momentum of an isolated

system of particles is conserved.

Reason: The law of conservation of momentum

follows from the second and third law of motion.

A. If both assertion and reason are true and

reason is the correct explanation of assertion.

B. If both assertion and reason are true and

reason is the not correct explanation of

assertion.

C. If assertion is true but reason is false

D. If both assertion and reason are false.

Answer: B

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12. Assertion: Friction opposes relative motion and

thereby dissipates power in the form of heat.

Reason: Friction is always an undesirable force.

A. If both assertion and reason are true and

reason is the correct explanation of assertion.

B. If both assertion and reason are true and

reason is the not correct explanation of

assertion.
 C. If assertion is true but reason is false

D. If both assertion and reason are false.

Answer: C

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13. Assertion: On a rainy day, it is difficult to drive a

car or bus at high speed.

Reason: The value of coefficient of friction is

lowered due to wetting of the surface.

 A. If both assertion and reason are true and

reason is the correct explanation of assertion.

B. If both assertion and reason are true and

reason is the not correct explanation of

assertion.

C. If assertion is true but reason is false

D. If both assertion and reason are false.

Answer: A

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14. Assertion : Static friction is a self-adjusting force

upto its limit μs N where μs is the coefficient of

static friction.

Reason: One can use the equation fs = μs N only

when the maximum value of static friction comes

into play

A. If both assertion and reason are true and

reason is the correct explanation of assertion.

B. If both assertion and reason are true and

reason is the not correct explanation of

assertion.
 C. If assertion is true but reason is false

D. If both assertion and reason are false.

Answer: B

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15. Assertion: The familiar equation mg = R for a

body on a table is true only if the body is in

equilibrium.

reason: The equality of mg and R has no

connection with the third law.

 A. If both assertion and reason are true and

reason is the correct explanation of assertion.

B. If both assertion and reason are true and

reason is the not correct explanation of

assertion.

C. If assertion is true but reason is false

D. If both assertion and reason are false.

Answer: B

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Others
1. Physical independence of force is a Consequcnce

of

A. first law of motion

B. second law of motion

C. third law of motion

D. all of these laws

Answer: A

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2. An astronaut accidentally gets separated out his

small spaceship accelerating in interstellar space at

a constant rate of 100ms

−2
. What is the

acceleration of the astronaut the instant after he is

outside the spaceship? (Assume that there are no

nearby stars to exert gravitional force on him)

A. zero

B. 10ms −2

C. 50ms −2

D. 100ms −2

Answer: A
 Watch Video Solution

3. Newton's second law of motion is

dp
A. F =
dt

B. F = mv

C. F = mv
2

D. F = m v
2

Answer: A

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4. Which one of the following statement is not ture
→
about Newton's second law of motion F ?
−
−→
= ma

A. The second law of motion is consistent with

the first law

B. The second law of motion is a vector law.

C. The second law of motion is applicable to a

single point particle.

D. The second law of motion is not applicable to

a single point particle.

Answer: D
 Watch Video Solution

→
5. The relation , cannot be deduced from
−
−→
F = ma

Newton's second law, if

A. force depends on time

B. momentum depends on time

C. acceleration depends on time

D. mass depends on time

Answer: D

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6. A large force is acting on a body for a short time.

The impulse imparted is equal to the change in

A. acceleration

B. momentum

C. energy

D. velocity

Answer: B

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7. Which one of the following is not force

 A. impulse

B. Tension

C. Thrust

D. Weight

Answer: A

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8. The motion of a particle of mass m is described

1
by y = ut +
2
gt . Find the force acting on the
2

particale .
 A. mg

μ
B.
t

C. 2mg

2μ
D.
t

Answer: A

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9. A constant force acting on a body of mass of 5 kg

change its speed from 5ms

−1
to 10ms
−1
in 10s

without changing the direction of motion. The force

acting on the body is

 A. 1.5N

B. 2N

C. 2.5N

D. 5N

Answer: C

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10. A bullet of mass 40g moving with a speed of

90ms
−1
enters a heavy wooden block and is

stopped after a direction of 60cm. The average

resistive force exered by the block on the bullet is

 A. 180 N

B. 220 N

C. 270 N

D. 320 N

Answer: C

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11. A body under the action of a force

→
F = 6 î − 8 ĵN acquires an acceleration of 5ms −2

. The mass of the body is

 A. 2kg

B. 5kg

C. 4kg

D. 6kg

Answer: A

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12. A constant retarding force of 50N is apllied to a

body of mass 10kg moving initially with a speed of

10ms
−1
. The body comes to rest after
 A. 2s

B. 4s

C. 6s

D. 8s

Answer: A

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13. A body of mass 5 kg starts from the origin with

an initial velocity . If a
→ −1
u = (30 î + 40 ĵ)ms

constant force ( − 6 î − 5 ĵ)N acts on the body,

the time in which the y-component of the velocity

becomes zero is

A. 5s

B. 20s

C. 40s

D. 80s

Answer: C

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14. A body of mass 0.4kg starting at origin at t = 0

with a speed of 10ms

−1
in the positive x-axis

direction is subjected to a constant F = 8 N

towards negative x-axis. The position of body after

25s is

A. − 6000m

B. − 8000m

C. + 4000m

D. + 7000m

Answer: A

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15. The force on a rocket moving with a veloctiy 300

m/s is 210N. The rate of consumption of fuel of

rocket is

A. 0.07kgs −1

B. 1.4kgs −1

C. 0.7kgs −1

D. 10.7kgs −1

Answer: C

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16. A ball of mass m strikes a rigid walJ with speed u

and rebounds with the same speed. The impulse

imparted to the ball by the wall is

A. 2mu

B. mu

C. zero

D. − 2mu

Answer: D

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17. A batsman hits back a ball straight in the

direction of the bowler without changing its initial

speed of 12ms −1
. If the mass of the ball is 0.15 kg ,

determine the impulse imparted to the ball .

(Assume linear motion of the ball).

A. 1.8N s

B. 2.8N s

C. 3.6N s

D. 4.2N s

Answer: C

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18. Figure shows (x,t) (y,t) diagram of a particle

moving in 2-dimensions.

If the particle has a mass of 500 g , find the force

(direction and magnitude) acting on the particle .

A. 1N along y-axis

B. 1N along x-axis

C. 0.5N along x-axis

 D. 0.5N along y-axis

Answer: A

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19. Figure shows the position-time graph of a

particle of mass 4kg. Let the force on the particle

for t < 0 , lt,4s ,

0 < t t > 4s be F1 , F2 and F3
respectively. Then

A. F 1 = F2 = F3 = 0

B. F 1 > F2 = F3

C. F 1 > F2 > F3

D. F 1 < F2 < F3

Answer: A

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20. Figure shows the position-time (x-t) graph of

one dimensional motion of a mass 500g. What is

the time interval between two consecutive impulses

received by the body?

A. 2s

B. 4s

C. 6s

D. 8s
Answer: A

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21. The position time graph of a body of mass 2kg is

as given in What is the impulse on the body at

t = 0 s and t = 4s ?

2
A. kgms
−1

2
B. − kgms
−1

3
C. kgms
−1

3
D. − kgms
−1

2
Answer: D

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22. We can derive Newton's

A. second and third laws from the first law.

B. first and second laws from the third law

C. third and first laws from the second law.

D. all the three laws are independent of each

other.

Answer: C
 Watch Video Solution

23. Which of the following statement is not true

regarding the Newton's third law of motion?

A. To every action there is always an equal and

opposite reaction.

B. Action and reaction act on the same body.

C. There is no cause-effect relation between

action and reaction.

D. Action and reaction forces are simultaneous

forces.
Answer: B

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24. The driver of a car travelling at velocity v

suddenly see a broad wall in front of him at a

distance d. He should

A. break sharply

B. turn sharply

C. both (a) and (b)

D. none of these
Answer: A

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25. Which of the following statements is incorrect?

A. A cricketer moves his hands backwards while

holding a catch.

B. A person from Hing from a certain height

receives more iniuries when he falls on a

cemented floor than when he falls on a heap

of sand.
 C. It is easier lo push a lawn mower than to pull

it.

D. Mountain roads are generally made winding

upwards rather than going strainght up.

Answer: C

View Text Solution

26. Which of the following statements is incorrect?

A. A -q, B -p, C-r, D-s

B. A-p,B-q,C-r,D-s

C. A-s,B-r,C-q,D-p

D. A-s, B-q, C-r, D-p

Answer: C

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27. A rocket is going upward with acceleration

motion. A man string in it feels his weight increased

5 time his own weight. If the mass of the rocket

including that of the man is 4

1.0 × 10 kg , how

much force is being applied by rocket engine?

(T akeg = 10ms
−2
) .

A. 5 × 104
N

B. 5 × 105
N

C. 5 × 108
N

D. 2 × 104
N
Answer: B

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28. Ten one-rupee coins are put on top each other

on a table. Each coin has a mass m. The rection of

the 6
th
coin (counted from the bottom) on the th
7

coin is

A. 4mg

B. 6mg

C. 7mg

D. 3mg
Answer: A

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29. A cork of mass 10 g is floating on water. The net

force acting on the cork is

A. 10N

B. 10 −3
N

C. 10 −2
N

D. zero

Answer: D
 Watch Video Solution

30. A stone of mass l kg is lying on the floor of a

train which is accelerating with 1ms

−2
The net

force acting on the stone is

A. zero

B. 1N

C. 5N

D. 10N

Answer: B

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31. A stream of water flowing horizontally with a

speed of 15ms
−1
pushes out of a tube of cross

sectional area 10
−2
m
2
and hits a vertical wall near

by what is the force exerted on the wall by the

impact of water assuming.that it does not rebound?

(Density of water = 1000kgm

3
)

A. 1.25 × 10 3
N

B. 2.25 × 10 3
N

C. 3.25 × 10 3
N

D. 4.25 × 10 3
N
Answer: B

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32. A steam of water flowing horizontally with a

speed of 25m
s −1
gushes out of a tube of cross-

sectional area 10
−3
m
2
, and hits at a vertical wall

nearby. What is the force exerted on the wall by the

impact of water

A. 125N

B. 625N

C. − 650N
 D. − 1125N

Answer: B

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33. A rocket with a lift-off mass 4

2 × 10 kg is blasted

upwards with an initial acceleration of 5ms

−2
. The

initial thrust of the blast is (Take g = 10ms

−2
)

A. 2 × 10 5
N

B. 3 × 10 5
N

C. 4 × 10 5
N
 D. 5 × 105
N

Answer: B

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34. A ball of mass m strikes a rigid walJ with speed u

and rebounds with the same speed. The impulse

imparted to the ball by the wall is

∘
mu sin30
A.
t

∘
2mu sin30
B.
t

∘
mu cos30
C.
t

∘
2mu cos30
D.
t
Answer: D

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35. A rocket of initial mass 6000kg ejects mass at a

constant rate of 16kg / s with constant relative

speed of 11m / s What is the acceleration of the

rocket one minute after blast ?

A. 25ms −2

B. 50ms −2

C. 10ms −2

D. 35ms −2
Answer: D

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36. Two billiard ball A and B each of mass 50g and

moving in opposite direction with speed of 5ms

−1

each, collide and rebound with the same speed. The

impulse imparted to each ball is

A. 0.25kgms −1

B. 0.5kgms −1

C. 0.8kgms −1

D. 0.125kgms −1
Answer: B

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