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# Practice Test - Circular Motion (BMSAP) JEE Notes | EduRev

## JEE : Practice Test - Circular Motion (BMSAP) JEE Notes | EduRev

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1
PRACTICE SET
CIRCULAR MOTION
CODE- 2017                   Time: 25 mins.                   Max. Marks. 60
Topics Covered: Application of Circular Motion in simple situations
Level : Basic Conceptual Level

INSTRUCTIONS:   Problems (1-15)  are Single Answer Correct Type, 4 marks each for correct option and -1 for
every wrong attempt.
1.  A ball of mass 0.1 kg is whirled in a horizontal
circle of radius 1 m by means of a string at an
initial speed of 10 r.p.m.  Keeping the radius
constant, the tension in the string is reduced to
one quarter of its initial value. The new speed is

(a) 5 r.p.m.   (b) 10 r.p.m.
(c) 20 r.p.m.  (d) 14 r.p.m.
2. Three identical particles are joined together by a
thread as shown in figure.  All the three particles
are moving in a horizontal plane. If the velocity
of the outermost particle is v
0
, then the ratio of
tensions in the three sections of the string is

(a) 3 : 5 : 7   (b) 3 : 4 : 5
(c) 7 : 11 : 6  (d) 3 : 5 : 6
3. A stone of mass 1 kg tied to the end of a string of
length 1 m, is whirled in a horizontal circle with a
uniform angular velocity of 2 rad/s. The tension
of the string is (in N)
(a) 2    (b)
3
1

(c) 4   (d)
4
1

4. A cord can bear a maximum force of 100 N
without breaking. A body of mass 1 kg tied to
one end of a cord of length 1 m is revolved in a
horizontal plane. What is the maximum linear
speed of the body so that the cord does not break
(a) 10 m/s   (b) 20 m/s
(c) 25 m/s   (d) 30 m/s
5. A mass is supported on a frictionless horizontal
surface. It is attached to a string and rotates about
a fixed centre at an angular velocity ?
0
. If the
length of the string and angular velocity are
doubled, the tension in the string which was
initially T
0
is now
(a) T
0
(b) T
0
/2
(c) 4T
0
(d) 8T
0

6. A stone is rotated steadily in a horizontal circle
with a period T by a string of length l. If the
tension in the string is kept constant and l
increases by 1%, what is the percentage change
in T
(a) 1%   (b) 0.5%
(c) 2%   (d) 0.25%
7. If mass speed and radius of rotation of a body
moving in a circular path are all increased by
50%, the necessary force required to maintain the
body moving in the circular path will have to be
increased by
(a) 225%   (b) 125%
(c) 150%   (d) 100%

l l l
O A B C

Page 2

1
PRACTICE SET
CIRCULAR MOTION
CODE- 2017                   Time: 25 mins.                   Max. Marks. 60
Topics Covered: Application of Circular Motion in simple situations
Level : Basic Conceptual Level

INSTRUCTIONS:   Problems (1-15)  are Single Answer Correct Type, 4 marks each for correct option and -1 for
every wrong attempt.
1.  A ball of mass 0.1 kg is whirled in a horizontal
circle of radius 1 m by means of a string at an
initial speed of 10 r.p.m.  Keeping the radius
constant, the tension in the string is reduced to
one quarter of its initial value. The new speed is

(a) 5 r.p.m.   (b) 10 r.p.m.
(c) 20 r.p.m.  (d) 14 r.p.m.
2. Three identical particles are joined together by a
thread as shown in figure.  All the three particles
are moving in a horizontal plane. If the velocity
of the outermost particle is v
0
, then the ratio of
tensions in the three sections of the string is

(a) 3 : 5 : 7   (b) 3 : 4 : 5
(c) 7 : 11 : 6  (d) 3 : 5 : 6
3. A stone of mass 1 kg tied to the end of a string of
length 1 m, is whirled in a horizontal circle with a
uniform angular velocity of 2 rad/s. The tension
of the string is (in N)
(a) 2    (b)
3
1

(c) 4   (d)
4
1

4. A cord can bear a maximum force of 100 N
without breaking. A body of mass 1 kg tied to
one end of a cord of length 1 m is revolved in a
horizontal plane. What is the maximum linear
speed of the body so that the cord does not break
(a) 10 m/s   (b) 20 m/s
(c) 25 m/s   (d) 30 m/s
5. A mass is supported on a frictionless horizontal
surface. It is attached to a string and rotates about
a fixed centre at an angular velocity ?
0
. If the
length of the string and angular velocity are
doubled, the tension in the string which was
initially T
0
is now
(a) T
0
(b) T
0
/2
(c) 4T
0
(d) 8T
0

6. A stone is rotated steadily in a horizontal circle
with a period T by a string of length l. If the
tension in the string is kept constant and l
increases by 1%, what is the percentage change
in T
(a) 1%   (b) 0.5%
(c) 2%   (d) 0.25%
7. If mass speed and radius of rotation of a body
moving in a circular path are all increased by
50%, the necessary force required to maintain the
body moving in the circular path will have to be
increased by
(a) 225%   (b) 125%
(c) 150%   (d) 100%

l l l
O A B C

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2
PRACTICE SET
CIRCULAR MOTION
8. Two masses m and M are connected by a light
string that passes through a smooth hole O at the
centre of a table. Mass m lies on the table and M
hangs vertically. m is moved round in a
horizontal circle with O as the centre. If l is the
length of the string from O to m then the
frequency with which m should revolve so that
M remains stationary is

(a)
l m
Mg
? 2
1
(b)
l m
Mg
?
1

(c)
Mg
l m
? 2
1
(d)
Mg
l m
?
1

9.  A particle of mass M moves with constant speed
along a circular path of radius r under the action
of a force F.  Its speed is
(a)
m
F r
(b)
r
F

(c) r m F   (d)
r m
F

10. A motor cycle driver doubles its velocity when he
is having a turn. The force exerted outwardly will
be
(a) Double   (b) Half
(c) 4 times   (d)
4
1
times
11. A body is performing circular motion. An
observer
1
O is sitting at the centre of the circle
and another observer
2
O is sitting on the body.
The centrifugal force is experienced by the
observer
(a)
1
O only  (b)
2
O only
(c)  Both by
1
O and
2
O (d) None of these
12. Find the maximum velocity for overturn for a car
moved on a circular track of radius m 100 . The
coefficient of friction between the road and tyre
is 2 . 0
(a) s m / 14 . 0  (b) s m / 140
(c) s km / 4 . 1  (d) s m / 14
13. When the road is dry and the coefficient of
friction is ? , the maximum speed of a car in a
circular path is s m / 10 . If the road becomes wet
and
2
?
? ? ? , what is the maximum speed
permitted
(a) s m / 5   (b) s m / 10
(c) s m / 2 10  (d) s m / 2 5
14. The coefficient of friction between the tyres and
the road is 0.25. The maximum speed with which
a car can be driven round a curve of radius 40 m
with skidding is (assume g = 10 ms
–2
)
(a)
1
40
?
ms  (b)
1
20
?
ms
(c)
1
15
?
ms  (d)
1
10
?
ms
15. A boy on a cycle pedals around a circle of 20
metres radius at a speed of 20 metres/sec. The
combined mass of the boy and the cycle is kg 90 .
The angle that the cycle makes with the vertical
so that it may not fall is
(a) tan
-1
(3)  (b) tan
-1
(2)
(c) tan
-1
( ?3)  (d) tan
-1
( ?2)

M
m

O

l

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