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17/09/2020 1:07 pm
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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 negligible.]
(1) 21J
(2) 23 J
(3) 20 J
(4) 19 J
1 Answer
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17/09/2020 1:10 pm
Correct answer: (1) 21 J
Explanation:
Conservation of linear momentum
0.1 × 20 = (0.1 + 1.9) × v
v = 1 m/s
Using work energy theorem Wg = Δk
2 × g × 1 = k - 1/2 x 2 x 12
∴ k = 21 J
This post was modified 5 years ago by nikhil04