Rotation 2 Question 3

3. A particle of mass 20g is released with an initial velocity 5 m/s along the curve from the point A, as shown in the figure. The point A is at height h from point B. The particle slides along the frictionless surface. When the particle reaches point B, its angular momentum about O will be (Take, g=10m/s2 )

(a) 8kgm2/s

(b) 3kgm2/s

(c) 2kgm2/s

(d) 6kgm2/s

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Answer:

Correct Answer: 3. (d)

Solution:

  1. The given figure is shown below as

As friction is absent, energy at A= energy at B

12mvA2+mgh=12mvB2vA2+2gh=vB2 or vB2=(5)2+2×10×10=225vB=15ms1

Angular momentum about point ’ O ‘,

=mvBrB=20×103×15×20=6kgm2s1



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