1
JEE Main 2021 (Online) 18th March Evening Shift
+4
-1
An object of mass m1 collides with another object of mass m2, which is at rest. After the collision the objects move with equal speeds in opposite direction. The ratio of the masses m2 : m1 is :
A
1 : 1
B
3 : 1
C
2 : 1
D
1 : 2
2
JEE Main 2021 (Online) 17th March Evening Shift
+4
-1
Two identical blocks A and B each of mass m resting on the smooth horizontal floor are connected by a light spring of natural length L and spring constant K. A third block C of mass m moving with a speed v along the line joining A and B collides with A. The maximum compression in the spring is

A
$$\sqrt {{{mv} \over K}}$$
B
$$\sqrt {{m \over {2K}}}$$
C
$$\sqrt {{{mv} \over {2K}}}$$
D
$$v\sqrt {{m \over {2K}}}$$
3
JEE Main 2021 (Online) 16th March Evening Shift
+4
-1
A large block of wood of mass M = 5.99 kg is hanging from two long massless cords. A bullet of mass m = 10 g is fired into the block and gets embedded in it. The (block + bullet) then swing upwards, their centre of mass rising a vertical distance h = 9.8 cm before the (block + bullet) pendulum comes momentarily to rest at the end of its arc. The speed of the bullet just before collision is :
(take g = 9.8 ms-2)

A
831.4 m/s
B
811.4 m/s
C
841.4 m/s
D
821.4 m/s
4
JEE Main 2021 (Online) 16th March Morning Shift
+4
-1
Four equal masses, m each are placed at the comers of a square of length (l) as shown in the figure. The moment of inertia of the system about an axis passing through A and parallel to DB would be :

A
$$\sqrt 3$$ ml2
B
2 ml2
C
ml2
D
3 ml2
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