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NEET 2025 · Work-Energy Theorem

Work-Energy Theorem question from NEET 2025

Q5NEET 2025Easy

Work-Energy Theorem

The kinetic energies of two similar cars AA and BB are 100 J and 225 J respectively. On applying brakes, car AA stops after 1000 m and car BB stops after 1500 m. If FAF_A and FBF_B are the forces applied by the brakes on cars AA and BB respectively, then the ratio of FAFB\frac{F_A}{F_B} is

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Answer: (d)

  1. Work-energy theorem: braking force ×\times stopping distance == initial KE, so F=KdF = \frac{K}{d}.
  2. FA=1001000=0.1 NF_A = \frac{100}{1000} = 0.1\text{ N}, FB=2251500=0.15 NF_B = \frac{225}{1500} = 0.15\text{ N}
  3. FAFB=0.10.15=23\frac{F_A}{F_B} = \frac{0.1}{0.15} = \frac{2}{3}
  4. So the answer is (d) 23\frac{2}{3}.
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