JEE Main 2021 (Online) 24th February Evening Shift
MCQ (Single Correct Answer)
+4
-1
A circular hole of radius $$\left( {{a \over 2}} \right)$$ is cut out of a circular disc of radius 'a' as shown in figure. The centroid of the remaining circular portion with respect to point 'O' will be :
A
$${1 \over 6}a$$
B
$${2 \over 3}a$$
C
$${5 \over 6}a$$
D
$${10 \over 11}a$$
2
JEE Main 2020 (Online) 6th September Evening Slot
MCQ (Single Correct Answer)
+4
-1
Particle A of mass m1
moving with velocity $$\left( {\sqrt3\widehat i + \widehat j} \right)m{s^{ - 1}}$$ collides with another particle B of mass m2
which is at rest initially. Let $$\overrightarrow {{V_1}} $$
and $$\overrightarrow {{V_2}} $$
be the velocities of particles A and B after collision
respectively. If m1
= 2m2
and after collision $$\overrightarrow {{V_1}} = $$$$\left( {\widehat i + \sqrt 3 \widehat j} \right)$$
, the angle between $$\overrightarrow {{V_1}} $$
and $$\overrightarrow {{V_2}} $$
is :
A
105o
B
15o
C
-45o
D
60o
3
JEE Main 2020 (Online) 4th September Morning Slot
MCQ (Single Correct Answer)
+4
-1
Blocks of masses m, 2m, 4m and 8m are arranged in a line on a frictionless floor. Another block of
mass m, moving with speed v along the same line (see figure) collides with mass m in perfectly
inelastic manner. All the subsequent collisions are also perfectly inelastic. By the time the last block
of mass 8m starts moving the total energy loss is p% of the original energy. Value of 'p' is close to :
A
37
B
77
C
87
D
94
4
JEE Main 2020 (Online) 3rd September Evening Slot
MCQ (Single Correct Answer)
+4
-1
A block of mass 1.9 kg is at rest at the edge of a table, of height 1 m. A bullet of mass 0.1 kg
collides with the block and sticks to it. If the velocity of the bullet is 20 m/s in the horizontal
direction just before the collision then the kinetic energy just before the combined system strikes
the floor, is [Take g = 10 m/s2
. Assume there is no rotational motion and loss of energy after the
collision is negligable.]