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JEE Main 2021 (18 Mar, Shift 1) · Conservation of Energy

Conservation of Energy question from JEE Main 2021 (18 Mar, Shift 1)

Q22JEE Main 2021 · 18 MAR · SHIFT 1Easy

Conservation of Energy

As shown in the figure, a particle of mass 10 kg is placed at a point A. When the particle is slightly displaced to its right, it starts moving and reaches the point B. The speed of the particle at B is x m/s. (Take g = 10 m/s2)

The value of 'x' to the nearest integer is __________.

Figure

Numerical answer type. Work it out, then open the answer.

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Answer: 10

  1. No friction, so 12mv2=mg Δh\frac{1}{2}mv^2 = mg\,\Delta h (mass cancels).
  2. Height drop from A (10 m) to B (5 m): Δh=5 m\Delta h = 5\text{ m}.
  3. v=2×10×5=100=10 m/sv = \sqrt{2 \times 10 \times 5} = \sqrt{100} = 10\text{ m/s}
  4. So x=10x = 10.
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