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JEE Main 2020 (7 Jan, Shift 1) · Conservation of Energy

Conservation of Energy question from JEE Main 2020 (7 Jan, Shift 1)

Q27JEE Main 2020 · 7 JAN · SHIFT 1Medium

Conservation of Energy

A particle (m = 1 kg) slides down a frictionless track (AOC) starting from rest at a point A (height 2 m). After reaching C, the particle continues to move freely in air as a projectile. When it reaches its highest point P (height 1 m), the kinetic energy of the particle (in J) is:

(Figure drawn is schematic and not to scale; take g = 10 ms-2)

Figure

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

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Answer: 10

  1. No friction or air drag, so total mechanical energy is conserved.
  2. At A (rest, 2 m): E=mghA=1×10×2=20 JE = mgh_A = 1 \times 10 \times 2 = 20\text{ J}.
  3. At P (1 m): UP=1×10×1=10 JU_P = 1 \times 10 \times 1 = 10\text{ J}
  4. KP=20−10=10 JK_P = 20 - 10 = 10\text{ J}
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