Motion in a Plane- 2 Practice Questions - DPP for NEET

 Page 1


DIRECTIONS (Q.1-Q.21) : There are 21 multiple choice
questions. Each question has 4 choices (a), (b), (c) and (d), out
of which ONLY ONE choice is correct.
Q.1 A particle completes 1.5 revolutions in a circular path of
radius 2 cm. The angular displacement of the particle will
be – (in radian)
(a) 6 p (b) 3 p (c) 2 p (d) p
Q.2 A particle revolving in a circular path completes first one
third of circumference in 2 sec, while next one third in 1
sec. The average angular velocity of particle will be –  (in
rad/sec)
(a)2p/3 (b) p/3 (c)4p/3 (d)5p/3
Q.3 The ratio of angular speeds of minute hand and hour hand
of a watch is -
(a) 1 : 12 (b) 6 : 1 (c) 12 : 1 (d) 1 : 6
Q.4 The angular displacement of a particle is given by
q = w
0
t + 
1
2
at
2
, where w
0
 and a are constant and
w
0
 = 1 rad/sec, a = 1.5 rad/sec
2
. The angular velocity at
time, t = 2 sec will be (in rad/sec) -
(a)1 (b)5
(c)3 (d)4
Q.5 The magnitude of the linear acceleration of the particle
moving in a circle of radius 10 cm with uniform speed
completing the circle in  4 s, will be -
(a)5p cm/s
2
(b) 2.5p cm/s
2
(c)5p
2 
cm/s
2
(d) 2.5p
2
 cm/s
2
Page 2


DIRECTIONS (Q.1-Q.21) : There are 21 multiple choice
questions. Each question has 4 choices (a), (b), (c) and (d), out
of which ONLY ONE choice is correct.
Q.1 A particle completes 1.5 revolutions in a circular path of
radius 2 cm. The angular displacement of the particle will
be – (in radian)
(a) 6 p (b) 3 p (c) 2 p (d) p
Q.2 A particle revolving in a circular path completes first one
third of circumference in 2 sec, while next one third in 1
sec. The average angular velocity of particle will be –  (in
rad/sec)
(a)2p/3 (b) p/3 (c)4p/3 (d)5p/3
Q.3 The ratio of angular speeds of minute hand and hour hand
of a watch is -
(a) 1 : 12 (b) 6 : 1 (c) 12 : 1 (d) 1 : 6
Q.4 The angular displacement of a particle is given by
q = w
0
t + 
1
2
at
2
, where w
0
 and a are constant and
w
0
 = 1 rad/sec, a = 1.5 rad/sec
2
. The angular velocity at
time, t = 2 sec will be (in rad/sec) -
(a)1 (b)5
(c)3 (d)4
Q.5 The magnitude of the linear acceleration of the particle
moving in a circle of radius 10 cm with uniform speed
completing the circle in  4 s, will be -
(a)5p cm/s
2
(b) 2.5p cm/s
2
(c)5p
2 
cm/s
2
(d) 2.5p
2
 cm/s
2
2
DPP/ P 07
Q.6 A cane filled with water is revolved in a vertical circle of
radius 4 m and water just does not fall down. The time
period of revolution will be –
(a) 1 s (b) 10 s
(c) 8 s (d) 4 s
Q.7 The length of second's hand in a watch is 1 cm. The change
in velocity of its tip in 15 second is -
(a)0 (b)
302
p
cm/s
(c)
30
p
cm/s (d)
2
30
p
 cm/s
Q.8 An electron is moving in a circular orbit of radius 5.3 × 10
–
11
 metre around the atomic nucleus at a rate of  6.6 × 10
15
revolutions per second. The centripetal force acting on the
electron will be -
(The mass of the electron is 9.1 × 10
–31
kg)
(a) 8.3 × 10
–8
N (b) 3.8 × 10
–8
N
(c) 4.15 × 10
–8
N (d) 2.07 × 10
–8
N
Q.9 An air craft executes a horizontal loop of radius 1 km with
a steady speed of 900 km/h. The ratio of centripetal
acceleration to that gravitational acceleration will be-
(a) 1 : 6.38 (b) 6. 38 : 1
(c) 2.25 : 9.8 (d) 2.5 : 9.8
Q.10 A car driver is negotiating a curve of radius 100 m with a
speed of 18 km/hr. The angle through which he has to lean
from the vertical will be -
(a) tan
–1
1
4
(b) tan
–1
1
40
(c) tan
–1
1
2
æö
÷ ç
÷
ç
÷
÷ ç
èø
(d) tan
–1
1
20
æö
÷ ç
÷
ç
÷
÷ ç
èø
Q.11 A particle moves in  a circle of radius 20cm with a linear
speed of 10m/s. The angular velocity will be -
(a) 50 rad/s (b) 100 rad/s
(c) 25 rad/s (d) 75 rad/s
Q.12 The angular velocity of a particle is given by w = 1.5 t – 3t
2
 +
2, the time when its angular acceleration decreases to be
zero will be -
(a) 25 sec (b) 0.25 sec
(c) 12 sec (d) 1.2 sec
Q.13 A particle is moving in a circular path with velocity varying
with time as v = 1.5t
2
 + 2t. If the radius of circular path is
2 cm, the angular acceleration at t = 2 sec will be -
(a) 4 rad/sec
2
(b) 40 rad/sec
2
(c) 400 rad/sec
2
(d) 0.4 rad/sec
2
Q.14 A grind stone starts from rest and has a constant-angular
acceleration of  4.0 rad/sec
2
.The angular displacement and
angular velocity, after 4 sec. will respectively be -
(a) 32 rad, 16 rad/s (b) 16 rad, 32 rad/s
(c) 64 rad, 32 rad/s (d) 32 rad, 64 rad/s
Q.15 The shaft of an electric motor starts from rest and on the
application of a torque, it gains an angular acceleration
given by a = 3t – t
2
 during the first 2 seconds after it starts
after which a = 0. The angular velocity after 6 sec will be -
(a) 10/3 rad/sec (b) 3/10 rad/sec
(c) 30/4 rad/sec (d) 4/30 rad/sec
Q.16 Using rectangular co-ordinates and the unit vectors i and
j, the vector expression for the acceleration a will be (r is
a position vector) -
(a) wr
2
(b)–w
2
r/2
(c)–2wr
2
(d)–w
2
r
Q.17 The vertical section of a road over a canal bridge in the
direction of its length is in the form of circle of radius 8.9
metre. Find the greatest speed at which the car can cross
this bridge without losing contact with the road at its highest
point, the center of gravity of the car being at a height h =
1.1 metre from the ground. (Take g = 10 m/sec
2
)
(a) 5 m/s (b) 7 m/s
(c) 10 m/s (d) 13 m/s
Q.18 The maximum speed at which a car can turn round a curve
of 30 metre radius on a level road if the coefficient of
friction between the tyres and the road is 0.4, will be -
(a) 10.84 m/s (b) 17.84 m/s
(c) 11.76 m/s (d) 9.02 m/s
Q.19 The angular speed with which the earth would have to rotate
on its axis so that a person on the equator would weigh
(3/5)
th
 as much as present, will be:
(Take the equatorial radius as 6400 km)
(a) 8.7 × 10
4
 rad/sec (b) 8.7 × 10
3
 rad/sec
(c) 7.8 × 10
4
 rad/sec (d) 7.8 × 10
3
 rad/sec
Page 3


DIRECTIONS (Q.1-Q.21) : There are 21 multiple choice
questions. Each question has 4 choices (a), (b), (c) and (d), out
of which ONLY ONE choice is correct.
Q.1 A particle completes 1.5 revolutions in a circular path of
radius 2 cm. The angular displacement of the particle will
be – (in radian)
(a) 6 p (b) 3 p (c) 2 p (d) p
Q.2 A particle revolving in a circular path completes first one
third of circumference in 2 sec, while next one third in 1
sec. The average angular velocity of particle will be –  (in
rad/sec)
(a)2p/3 (b) p/3 (c)4p/3 (d)5p/3
Q.3 The ratio of angular speeds of minute hand and hour hand
of a watch is -
(a) 1 : 12 (b) 6 : 1 (c) 12 : 1 (d) 1 : 6
Q.4 The angular displacement of a particle is given by
q = w
0
t + 
1
2
at
2
, where w
0
 and a are constant and
w
0
 = 1 rad/sec, a = 1.5 rad/sec
2
. The angular velocity at
time, t = 2 sec will be (in rad/sec) -
(a)1 (b)5
(c)3 (d)4
Q.5 The magnitude of the linear acceleration of the particle
moving in a circle of radius 10 cm with uniform speed
completing the circle in  4 s, will be -
(a)5p cm/s
2
(b) 2.5p cm/s
2
(c)5p
2 
cm/s
2
(d) 2.5p
2
 cm/s
2
2
DPP/ P 07
Q.6 A cane filled with water is revolved in a vertical circle of
radius 4 m and water just does not fall down. The time
period of revolution will be –
(a) 1 s (b) 10 s
(c) 8 s (d) 4 s
Q.7 The length of second's hand in a watch is 1 cm. The change
in velocity of its tip in 15 second is -
(a)0 (b)
302
p
cm/s
(c)
30
p
cm/s (d)
2
30
p
 cm/s
Q.8 An electron is moving in a circular orbit of radius 5.3 × 10
–
11
 metre around the atomic nucleus at a rate of  6.6 × 10
15
revolutions per second. The centripetal force acting on the
electron will be -
(The mass of the electron is 9.1 × 10
–31
kg)
(a) 8.3 × 10
–8
N (b) 3.8 × 10
–8
N
(c) 4.15 × 10
–8
N (d) 2.07 × 10
–8
N
Q.9 An air craft executes a horizontal loop of radius 1 km with
a steady speed of 900 km/h. The ratio of centripetal
acceleration to that gravitational acceleration will be-
(a) 1 : 6.38 (b) 6. 38 : 1
(c) 2.25 : 9.8 (d) 2.5 : 9.8
Q.10 A car driver is negotiating a curve of radius 100 m with a
speed of 18 km/hr. The angle through which he has to lean
from the vertical will be -
(a) tan
–1
1
4
(b) tan
–1
1
40
(c) tan
–1
1
2
æö
÷ ç
÷
ç
÷
÷ ç
èø
(d) tan
–1
1
20
æö
÷ ç
÷
ç
÷
÷ ç
èø
Q.11 A particle moves in  a circle of radius 20cm with a linear
speed of 10m/s. The angular velocity will be -
(a) 50 rad/s (b) 100 rad/s
(c) 25 rad/s (d) 75 rad/s
Q.12 The angular velocity of a particle is given by w = 1.5 t – 3t
2
 +
2, the time when its angular acceleration decreases to be
zero will be -
(a) 25 sec (b) 0.25 sec
(c) 12 sec (d) 1.2 sec
Q.13 A particle is moving in a circular path with velocity varying
with time as v = 1.5t
2
 + 2t. If the radius of circular path is
2 cm, the angular acceleration at t = 2 sec will be -
(a) 4 rad/sec
2
(b) 40 rad/sec
2
(c) 400 rad/sec
2
(d) 0.4 rad/sec
2
Q.14 A grind stone starts from rest and has a constant-angular
acceleration of  4.0 rad/sec
2
.The angular displacement and
angular velocity, after 4 sec. will respectively be -
(a) 32 rad, 16 rad/s (b) 16 rad, 32 rad/s
(c) 64 rad, 32 rad/s (d) 32 rad, 64 rad/s
Q.15 The shaft of an electric motor starts from rest and on the
application of a torque, it gains an angular acceleration
given by a = 3t – t
2
 during the first 2 seconds after it starts
after which a = 0. The angular velocity after 6 sec will be -
(a) 10/3 rad/sec (b) 3/10 rad/sec
(c) 30/4 rad/sec (d) 4/30 rad/sec
Q.16 Using rectangular co-ordinates and the unit vectors i and
j, the vector expression for the acceleration a will be (r is
a position vector) -
(a) wr
2
(b)–w
2
r/2
(c)–2wr
2
(d)–w
2
r
Q.17 The vertical section of a road over a canal bridge in the
direction of its length is in the form of circle of radius 8.9
metre. Find the greatest speed at which the car can cross
this bridge without losing contact with the road at its highest
point, the center of gravity of the car being at a height h =
1.1 metre from the ground. (Take g = 10 m/sec
2
)
(a) 5 m/s (b) 7 m/s
(c) 10 m/s (d) 13 m/s
Q.18 The maximum speed at which a car can turn round a curve
of 30 metre radius on a level road if the coefficient of
friction between the tyres and the road is 0.4, will be -
(a) 10.84 m/s (b) 17.84 m/s
(c) 11.76 m/s (d) 9.02 m/s
Q.19 The angular speed with which the earth would have to rotate
on its axis so that a person on the equator would weigh
(3/5)
th
 as much as present, will be:
(Take the equatorial radius as 6400 km)
(a) 8.7 × 10
4
 rad/sec (b) 8.7 × 10
3
 rad/sec
(c) 7.8 × 10
4
 rad/sec (d) 7.8 × 10
3
 rad/sec
DPP/ P 07
3
Q.20 A smooth table is placed horizontally and a spring of
unstreched length l
0
 and force constant k has one end fixed
to its centre. To the other end of the spring is attached a
mass m which is making n revolution per second around
the centre. Tension in the spring will be
(a)4p
2
 m  k l
0
 n
2
/ (k – 4p
2
 m n
2
)
(b)4p
2
 m  k l
0
 n
2
/ (k + 4p
2
 m n
2
)
(c)2p
2
 m  k l
0
 n
2
/ (k – 4p
2
 m n
2
)
(d)2p m  k l
0
 n
2
/ (k – 4p
2
 m n
2
)
Q.21A motor car is travelling at 30 m/s on a circular road of
radius 500 m. It is increasing its speed at the rate of 2 m/
s
2
. Its net acceleration is (in m/s
2
) –
(a)2 (b) 1. 8
(c) 2.7 (d)0
DIRECTIONS (Q.22-Q.24) : In the following questions,
more than one of the answers  given are correct. Select the
correct answers and mark it according to the following
codes:
Codes :
(a) 1, 2 and 3 are correct (b) 1 and 2 are correct
(c) 2 and 4 are correct (d) 1 and 3 are correct
Q.22 Three identical particles are connected by three strings as
shown in fig. These particles are revolving in a horizontal
circle. The velocity of outer most particle is v, then choose
correct relation for T
1
,T
2
 and T
3
(where T
1
 is tension in the outer most string etc.)
O
m m m
l l l
(1) T
1
 = 
2
A
mv
3 l
(2) T
2
  = 
2
A
5mv
9 l
(3) T
3
= 
2
A
6mv
9 l
(4) T
3
 = 
2
A
5mv
9 l
Q.23A particle describes a horizontal circle on the smooth
surface of an inverted cone. The height of the plane of the
circle above the vertex is 9.8 cm, then choose the correct
options
(1) The speed of the particle will be 0.98 m/s
(2) tan q  = 
2
rg
v
 (q is semi-apex angle)
(3) The speed of the particle will be 98 m/s
(4) tan q  = 
rg
v
 (q is semiapex angle)
Q.24Choose the correct statements
(1) Centripetal force is not a real force. It is only the
requirement for circular motion.
(2) Work done by centripetal force may or may not be
zero.
(3) Work done by centripetal force is always zero.
(4) Centripetal force is a fundamental force.
DIRECTIONS (Q.25-Q.27) : Read the passage given below
and answer the questions that follows :
The velocity of the particle changes moving on the curved path,
this change in velocity is brought by a force  known as centripetal
force and  the acceleration so produced in the body is known as
centripetal acceleration. The direction of centripetal force or
acceleration is always towards the centre of circular path.
Q.25A ball is fixed to the end of a string and is rotated in a
horizontal circle of radius 5 m with a speed of 10 m/sec.
The acceleration of the ball will be -
(a) 20 m/s
2
(b) 10 m/s
2
(c) 30 m/s
2
(d) 40 m/s
2
Q.26 A body of mass 2 kg lying on a smooth  surface is attached
to a string 3 m long and then whirled round in a horizontal
circle making 60 revolution per minute. The centripetal
acceleration will be-
(a) 118.4 m/s
2
(b) 1.18 m/s
2
(c) 2.368 m/s
2
(d) 23.68 m/s
2
Q.27 A body of mass 0.1 kg is moving on circular path of diameter
1.0 m at the rate of  10  revolutions per 31.4 seconds. The
centripetal force acting on the body is -
(a) 0.2 N (b) 0.4 N
(c) 2 N (d) 4 N
Page 4


DIRECTIONS (Q.1-Q.21) : There are 21 multiple choice
questions. Each question has 4 choices (a), (b), (c) and (d), out
of which ONLY ONE choice is correct.
Q.1 A particle completes 1.5 revolutions in a circular path of
radius 2 cm. The angular displacement of the particle will
be – (in radian)
(a) 6 p (b) 3 p (c) 2 p (d) p
Q.2 A particle revolving in a circular path completes first one
third of circumference in 2 sec, while next one third in 1
sec. The average angular velocity of particle will be –  (in
rad/sec)
(a)2p/3 (b) p/3 (c)4p/3 (d)5p/3
Q.3 The ratio of angular speeds of minute hand and hour hand
of a watch is -
(a) 1 : 12 (b) 6 : 1 (c) 12 : 1 (d) 1 : 6
Q.4 The angular displacement of a particle is given by
q = w
0
t + 
1
2
at
2
, where w
0
 and a are constant and
w
0
 = 1 rad/sec, a = 1.5 rad/sec
2
. The angular velocity at
time, t = 2 sec will be (in rad/sec) -
(a)1 (b)5
(c)3 (d)4
Q.5 The magnitude of the linear acceleration of the particle
moving in a circle of radius 10 cm with uniform speed
completing the circle in  4 s, will be -
(a)5p cm/s
2
(b) 2.5p cm/s
2
(c)5p
2 
cm/s
2
(d) 2.5p
2
 cm/s
2
2
DPP/ P 07
Q.6 A cane filled with water is revolved in a vertical circle of
radius 4 m and water just does not fall down. The time
period of revolution will be –
(a) 1 s (b) 10 s
(c) 8 s (d) 4 s
Q.7 The length of second's hand in a watch is 1 cm. The change
in velocity of its tip in 15 second is -
(a)0 (b)
302
p
cm/s
(c)
30
p
cm/s (d)
2
30
p
 cm/s
Q.8 An electron is moving in a circular orbit of radius 5.3 × 10
–
11
 metre around the atomic nucleus at a rate of  6.6 × 10
15
revolutions per second. The centripetal force acting on the
electron will be -
(The mass of the electron is 9.1 × 10
–31
kg)
(a) 8.3 × 10
–8
N (b) 3.8 × 10
–8
N
(c) 4.15 × 10
–8
N (d) 2.07 × 10
–8
N
Q.9 An air craft executes a horizontal loop of radius 1 km with
a steady speed of 900 km/h. The ratio of centripetal
acceleration to that gravitational acceleration will be-
(a) 1 : 6.38 (b) 6. 38 : 1
(c) 2.25 : 9.8 (d) 2.5 : 9.8
Q.10 A car driver is negotiating a curve of radius 100 m with a
speed of 18 km/hr. The angle through which he has to lean
from the vertical will be -
(a) tan
–1
1
4
(b) tan
–1
1
40
(c) tan
–1
1
2
æö
÷ ç
÷
ç
÷
÷ ç
èø
(d) tan
–1
1
20
æö
÷ ç
÷
ç
÷
÷ ç
èø
Q.11 A particle moves in  a circle of radius 20cm with a linear
speed of 10m/s. The angular velocity will be -
(a) 50 rad/s (b) 100 rad/s
(c) 25 rad/s (d) 75 rad/s
Q.12 The angular velocity of a particle is given by w = 1.5 t – 3t
2
 +
2, the time when its angular acceleration decreases to be
zero will be -
(a) 25 sec (b) 0.25 sec
(c) 12 sec (d) 1.2 sec
Q.13 A particle is moving in a circular path with velocity varying
with time as v = 1.5t
2
 + 2t. If the radius of circular path is
2 cm, the angular acceleration at t = 2 sec will be -
(a) 4 rad/sec
2
(b) 40 rad/sec
2
(c) 400 rad/sec
2
(d) 0.4 rad/sec
2
Q.14 A grind stone starts from rest and has a constant-angular
acceleration of  4.0 rad/sec
2
.The angular displacement and
angular velocity, after 4 sec. will respectively be -
(a) 32 rad, 16 rad/s (b) 16 rad, 32 rad/s
(c) 64 rad, 32 rad/s (d) 32 rad, 64 rad/s
Q.15 The shaft of an electric motor starts from rest and on the
application of a torque, it gains an angular acceleration
given by a = 3t – t
2
 during the first 2 seconds after it starts
after which a = 0. The angular velocity after 6 sec will be -
(a) 10/3 rad/sec (b) 3/10 rad/sec
(c) 30/4 rad/sec (d) 4/30 rad/sec
Q.16 Using rectangular co-ordinates and the unit vectors i and
j, the vector expression for the acceleration a will be (r is
a position vector) -
(a) wr
2
(b)–w
2
r/2
(c)–2wr
2
(d)–w
2
r
Q.17 The vertical section of a road over a canal bridge in the
direction of its length is in the form of circle of radius 8.9
metre. Find the greatest speed at which the car can cross
this bridge without losing contact with the road at its highest
point, the center of gravity of the car being at a height h =
1.1 metre from the ground. (Take g = 10 m/sec
2
)
(a) 5 m/s (b) 7 m/s
(c) 10 m/s (d) 13 m/s
Q.18 The maximum speed at which a car can turn round a curve
of 30 metre radius on a level road if the coefficient of
friction between the tyres and the road is 0.4, will be -
(a) 10.84 m/s (b) 17.84 m/s
(c) 11.76 m/s (d) 9.02 m/s
Q.19 The angular speed with which the earth would have to rotate
on its axis so that a person on the equator would weigh
(3/5)
th
 as much as present, will be:
(Take the equatorial radius as 6400 km)
(a) 8.7 × 10
4
 rad/sec (b) 8.7 × 10
3
 rad/sec
(c) 7.8 × 10
4
 rad/sec (d) 7.8 × 10
3
 rad/sec
DPP/ P 07
3
Q.20 A smooth table is placed horizontally and a spring of
unstreched length l
0
 and force constant k has one end fixed
to its centre. To the other end of the spring is attached a
mass m which is making n revolution per second around
the centre. Tension in the spring will be
(a)4p
2
 m  k l
0
 n
2
/ (k – 4p
2
 m n
2
)
(b)4p
2
 m  k l
0
 n
2
/ (k + 4p
2
 m n
2
)
(c)2p
2
 m  k l
0
 n
2
/ (k – 4p
2
 m n
2
)
(d)2p m  k l
0
 n
2
/ (k – 4p
2
 m n
2
)
Q.21A motor car is travelling at 30 m/s on a circular road of
radius 500 m. It is increasing its speed at the rate of 2 m/
s
2
. Its net acceleration is (in m/s
2
) –
(a)2 (b) 1. 8
(c) 2.7 (d)0
DIRECTIONS (Q.22-Q.24) : In the following questions,
more than one of the answers  given are correct. Select the
correct answers and mark it according to the following
codes:
Codes :
(a) 1, 2 and 3 are correct (b) 1 and 2 are correct
(c) 2 and 4 are correct (d) 1 and 3 are correct
Q.22 Three identical particles are connected by three strings as
shown in fig. These particles are revolving in a horizontal
circle. The velocity of outer most particle is v, then choose
correct relation for T
1
,T
2
 and T
3
(where T
1
 is tension in the outer most string etc.)
O
m m m
l l l
(1) T
1
 = 
2
A
mv
3 l
(2) T
2
  = 
2
A
5mv
9 l
(3) T
3
= 
2
A
6mv
9 l
(4) T
3
 = 
2
A
5mv
9 l
Q.23A particle describes a horizontal circle on the smooth
surface of an inverted cone. The height of the plane of the
circle above the vertex is 9.8 cm, then choose the correct
options
(1) The speed of the particle will be 0.98 m/s
(2) tan q  = 
2
rg
v
 (q is semi-apex angle)
(3) The speed of the particle will be 98 m/s
(4) tan q  = 
rg
v
 (q is semiapex angle)
Q.24Choose the correct statements
(1) Centripetal force is not a real force. It is only the
requirement for circular motion.
(2) Work done by centripetal force may or may not be
zero.
(3) Work done by centripetal force is always zero.
(4) Centripetal force is a fundamental force.
DIRECTIONS (Q.25-Q.27) : Read the passage given below
and answer the questions that follows :
The velocity of the particle changes moving on the curved path,
this change in velocity is brought by a force  known as centripetal
force and  the acceleration so produced in the body is known as
centripetal acceleration. The direction of centripetal force or
acceleration is always towards the centre of circular path.
Q.25A ball is fixed to the end of a string and is rotated in a
horizontal circle of radius 5 m with a speed of 10 m/sec.
The acceleration of the ball will be -
(a) 20 m/s
2
(b) 10 m/s
2
(c) 30 m/s
2
(d) 40 m/s
2
Q.26 A body of mass 2 kg lying on a smooth  surface is attached
to a string 3 m long and then whirled round in a horizontal
circle making 60 revolution per minute. The centripetal
acceleration will be-
(a) 118.4 m/s
2
(b) 1.18 m/s
2
(c) 2.368 m/s
2
(d) 23.68 m/s
2
Q.27 A body of mass 0.1 kg is moving on circular path of diameter
1.0 m at the rate of  10  revolutions per 31.4 seconds. The
centripetal force acting on the body is -
(a) 0.2 N (b) 0.4 N
(c) 2 N (d) 4 N
4
DPP/ P 07
DIRECTIONS (Q. 28-Q.30) : Each of these qu estions contains two
sta tements: S tatem ent-1 (Ass ertio n) an d S tatement-2 (Reaso n). E ach
of these questions has four alternative choices, only one of which is
the correct answer . Y ou have to select the correct choice.
(a) Statement-1 is True, Statement-2 is True; Statement-2 is a
correct explanation for  Statement-1.
(b) Statement-1 is True, Statement-2 is True; Statement-2 is
NOT a correct explanation for Statement-1.
(c) Statement -1 is False, Statement-2 is True.
(d) Statement -1 is True, Statement-2 is False.
Q.28 Statement - 1 : In non-uniform circular motion, velocity
vector and acceleration vector are not perpendicular to each
other.
Statement - 2 : In non-uniform circular motion, particle has
normal as well as tangential acceleration.
Q.29 Statement - 1  :A cyclist is cycling on rough horizontal
circular track with increasing speed. Then the frictional force
on cycle is always directed towards centre of the circular
track.
Statement - 2 : For a particle moving in a circle, radial
component of net force should be directed towards centre.
Q.30Statement - 1 :  If net force F
r
 acting on a system is
changing in direction only, the linear momentum 
() p
r
 of
system changes in direction.
Statement - 2 :  In case of uniform circular motion,
magnitude of linear momentum is constant but direction
of centripetal force changes at every instant.