Physics Times – July 2019

(Darren Dugan) #1
   

3 2 2 5/2 2 2
2

Cy x y x y
x

 
  

(^)  
3 2 2 5/
(2 )
2
Cy x y x

 
 
2 2 5/
y 3
F
Cxy x y
x
 
 

As
Fy Fx
x y
 

  the gravitational force is
conservative.
1.When a conservative force does positive work
on a body:
(a) The potential energy increases
(b) The potential energy decreases
(c) Total energy increases
(d) Total energy decreases
2.Which one of the following is not a
conservative force?
(a) Electrostatic force (b) Magnetic force
(c) Friction (d) Gravitational force
3.In which of the following cases can the work
done increase the potential energy?
(a) Conservative force only
(b) Non-conservative force only
(c) Neither conservative nor non-conservative
forces
(d) Both conservative and non-conservative
forces
4.Work done by a conservative force
(a) Never depends on path
(b) May depend on path
(c) Is not related to potential energy
(d) None of these
5.Work done by the conservative forces on a
system is equal to
(a) The change in kinetic energy of the system
(b) The (-ve) of change in potential energy of
the system
(c) The (-ve) change in total mechanical energy
of the system
(d) None of the above
6.Which of the following statements are correct?
A. If a particle moves opposite to the
conservative field, potential energy will
increases
B. If a particle moves in the direction of
conservative field, the potential energy will
increase
C. If a particle moves opposite to the
conservative field, work done by the field
will be positive
D. If a particle moves opposite to the conserv
ative field, work done by the field will be
negative
(a) A, C (b) A, D
(c) B, C (d) B, D
7.If W W andW1 2, 3 represent the work done in
moving a particle from A to B along three
different paths 1,2 and 3 respectively in the
gravitational field of a point mass m. Find the
correct relation between W W andW1 2, 3.
(a) W W W 1   2 3 (b) W W W 1   2 3
(c) W W W 1   2 3 (d) W W W 1   2 3
8.Negative of work done by the conservative
forces on a system is equal to :
(a) The change in kinetic energy of the system
(b) The change in potential energy of the
system
(c) The change in total mechanical energy of
the system
(d) None of these
9.Which of the following force is conservative
(a) 5 ˆj (b)  6 kˆ
(c) 2 ˆi (d) All of the above




  1. Which of the following is a conservative
    force?
    (a)^22














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xy i x yjˆ ˆ (b) xyi xy jˆ ˆ
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