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JEE MainPhysicsWork, Power and Energy

A small block is released from rest from the top of a smooth curved track. The track ends at the ground level. When the block is at a vertical height of 2 m above the ground, its speed is 4 5 m s ⁻¹ . If g = 10 m s ⁻² , the vertical height from which the block was released is:

Options

  1. A4 m
  2. B10 m
  3. C6 m
  4. D2 m

Correct answer

C. 6 m

Step-by-step solution

Let the initial height of the block be H . Applying conservation of mechanical energy between the release point and the point at height h = 2 m : m g H = m g h + 1 2 m v^2 Substituting the given values ( g = 10 m s ⁻² , h = 2 m , v = 4 5 m s ⁻¹ ): 10 H = 10 2 + 1 2 (4 5 )^2 10 H = 20 + 1 2 80 10 H = 20 + 40 = 60 H = 6 m Answer: 6 m

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