March 2011 - Career Point

8. Work done by electric force as the rod rotates from
unstable to stable equilibrium position is -
(A) q E L
(C) 3
4 q E L
(B) 3
2 q E L
(D)
4
3 q E L
9. If rod is displaced ttle from its stable equilibrium
position it executes SHM about vertical axis. Time
period of the SHM will be -
(A)
(C)
2π
3
2π
3
mL
QE
5mL
QE
(B) 2π
(D) 2π
5mL
3QE
mL
3QE
Paragraph # 2 (Ques. 10 to 12)
A small ball B of mass 'm' is suspended with light
inelastic string of length “L” from a block A of same
mass “m” which can move on smooth horizontal
surface as shown in figure. The ball is displaced by
angle θ from equilibrium position & then released :
A
A
B
C
D
P Q R S T
P Q R S T
P Q R S T
P Q R S T
P Q R S T
Mark your response in OMR sheet against the question
number of that question in section-II. + 8 marks will be
given for complete correct answer (i.e. +2 marks for
each correct row) and NO NEGATIVE MARKING for
wrong answer.
13. In the diagram shown in figure, all pulleys are
smooth and massless and strings are light. Match the
following :
F = 80N
L θ
1 kg
3 kg
4 kg
B
10. The displacement of block when ball reaches the
equilibrium position -
Lsin
θ
(A)
(B) L sin θ
2
(C) L
(D) None of these
11. Tension in the string when it is vertical -
(A) mg (B) mg(2 – cos θ)
(C) mg(3 – 2 cosθ) (D) None of these
12. Maximum velocity of block during subsequent
motion of the system after release of ball is :
(A) [gl(1 – cosθ)] 1/2
(B) [2gl(1 – cos θ)] 1/2
(C) [glcosθ] 1/2
(D) Information is in sufficient
SECTION – III
Matrix - Match Type
This section contains 2 questions (Questions 13, 14).
Each question contains statements given in two
columns which have to be matched. Statements (A, B,
C, D) in Column I have to be matched with statements
(P, Q, R, S, T) in Column II. The answers to these
questions have to be appropriately bubbled as
illustrated in the following example. If the correct
matches are A-P, A-S, A-T; B-Q, B-R; C-P, C-Q and
D-S, D-T then the correctly bubbled 4 × 5 matrix
should be as follows :
2 kg
Column -I
Column-II
(A) 1 kg block
(P) will remain stationary
(B) 2 kg block
(Q) will move down
(C) 3 kg block
(R) will move up
(D) 4 kg block (S) 5 m/s 2
(T) 10 m/s 2
14. In the system shown in figure, mass m is released from rest
from position A. Suppose potential energy of m at point A
with respect to point B is E. Dimensions of m are negligible
and all surfaces are smooth. When mass m reaches at point
B :
m
A
R
2m B
Column -I
Column-II
(A) Kinetic energy of m (P) E /3
(B) kinetic energy of 2m (Q) 2E/3
(C) Momentum of m (R)
4
mE
3
2
(D) Momentum of 2m (S) mE
3
(T) None
XtraEdge for IIT-JEE 69
MARCH 2011