IIT JEE Physics Final Revision Set 11

1. STATEMENT-1 : In an elastic collision
between two bodies, the relative speed of
the bodies after collision is equal to the
relative speed before the collision.
Because
STATEMENt-2 : In an elastic collision,
the linear momentum of the system is
conserved.

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 True, Statement-2 is
False.
d. Statement-1 is False, Statement-2 is
True.

Two discs A and B are mounted coaxially on a
vertical axle. The discs have moments of inertia
I and 2I respectively about the common axis.
Disc A is imparted an initial angular velocity 2ω
using the entire potential energy of a spring
compressed by a distance x1 . Disc B is
imparted an angular velocity w by a spring
having the same spring constant and constant
and compressed by a distance x2 . Both the
discs rotate in the clockwise direction.

2. The ratio of x1 /x2 is
a. 2 b. 1/2 c. √2 d. 1/√2


3. When disc B is brought in contact with
disc A, they acquire a common angular
velocity in time t. The average frictional
torque on one disc by the other during
this period is

a. 2Iω/3t b. 9Iω/2t c. 9Iω/4t s. 3Iω/2t

4. The loss of kinetic energy during the
above process is

a. Iω²/2 b. Iω²/3 c. Iω²/4 d. Iω²/6

5. Match column 1 items with column 2 items

Column 1

a. Transition
between two
atomic energy
levels

b. Electron
emission from
a material

c. Mosley’s law

d. Change of
photon
energy into
kinetic
energy of
electrons

Column 2

p. Characteristic Xrays
q. Photoelectric
effect
r. Hydrogen
spectrum
d.β-decay


Source: 2007 JEE paper 1