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KVPY2017PhysicsRotational Motion

Persons A and B are standing on the opposite sides of a 3.5 ~m wide water stream which they wish to cross. Each one of them has a rigid wooden plank whose mass can be neglected. However, each plank is only slightly longer than 3 ~m . So they decide to arrange them together as shown in the figure schematically. With B (mass 17 ~kg ) standing, the maximum mass of A , who can walk over the plank is close to,

Options

  1. A17 ~kg
  2. B65 ~kg .
  3. C80 ~kg .
  4. D105 ~kg .

Correct answer

C. 80 ~kg .

Step-by-step solution

N=10 ~m N 0.5=170 x 10 ~m 5 10 =170 x m = 170 x 5 Maximum value is near to 2.5 infact shift by less than 2.5 Maximum vlaue of m= 170 5 2.5=85 Opction (C) is correct

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