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NDA 1 2024 GAT, question 89

Topic: Physics

Q89

A metallic bob XX of mass mm is released from position AA. It collides elastically with another identical bob YY placed at rest at position BB on a horizontal frictionless table. The angle AOBAOB is 30∘30^{\circ}.

Figure for Q89

How high does the bob XX rise immediately after the collision ?

  1. (a) To the same height as that of position AA on the other side in the same trajectory
  2. (b) To half the height as that of position AA on the other side along the same trajectory
  3. (c) The same height at position AA
  4. (d) It stops at position BBCorrect answer

Solution.

Answer: (d) It stops at position BB

  1. In a head-on elastic collision between equal masses, the velocities are exchanged.
  2. The initially stationary bob Y takes X’s speed, and X becomes stationary at B.
  3. Therefore X does not rise immediately after the collision.