1
JEE Main 2020 (Online) 4th September Morning Slot
+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
2
JEE Main 2020 (Online) 3rd September Evening Slot
+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.]
A
23 J
B
21 J
C
20 J
D
19 J
3
JEE Main 2020 (Online) 3rd September Morning Slot
+4
-1
A block of mass m = 1 kg slides with velocity v = 6 m/s on a frictionless horizontal surface and collides with a uniform vertical rod and sticks to it as shown. The rod is pivoted about O and swings as a result of the collision making angle $$\theta$$ before momentarily coming to rest. If the rod has mass M = 2 kg, and length $$l$$ = 1 m, the value of $$\theta$$ is approximately :
(take g = 10 m/s2) A
63o
B
69o
C
55o
D
49
4
JEE Main 2020 (Online) 2nd September Morning Slot
+4
-1
A particle of mass m with an initial velocity $$u\widehat i$$ collides perfectly elastically with a mass 3 m at rest. It moves with a velocity $$v\widehat j$$ after collision, then, v is given by :
A
$$v = \sqrt {{2 \over 3}} u$$
B
$$v = {u \over {\sqrt 3 }}$$
C
$$v = {u \over {\sqrt 2 }}$$
D
$$v = {1 \over {\sqrt 6 }}u$$
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