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JEE Advanced2012PhysicsRotational MotionActual

Consider a disc rotating in the horizontal plane with a constant angular speed about its centre O . The disc has a shaded region on one side of the diameter and an unshaded region on the other side as shown in the figure. When the disc is in the orientation as shown, two pebbles P and Q are simultaneously projected at an angle towards R . The velocity of projection is in the y - z plane and is same for both pebbles w

Options

  1. AP lands in the shaded region and Q in the unshaded region.
  2. BP lands in the unshaded region and Q in the shaded region.
  3. CBoth P and Q land in the unshaded region.
  4. DBoth P and Q land in the shaded region.

Correct answer

C. Both P and Q land in the unshaded region.

Step-by-step solution

For 1 8 of rotation of disc, aligned t= 1 8 2 = 4 & x -coordinate of P &= R T &= R 4 >R 45^ aligned To reach the unshaded part, particle P needs to travel horizontal range >R 45^ 0.7 R But its range is less than R / 2 so it will land on shaded part. Q is near the origin, its velocity will be nearly along QR so it will land in unshaded part.

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