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NEET 2025
Exam
NEET
Year
2025
Subject
Physics
Chapter
Work, Power and Energy

NEET 2025 · Physics · Work, Power and Energy

The kinetic energies of two similar cars A and B are 100 J and 225...

The kinetic energies of two similar cars AA and BB are 100 J and 225 J respectively. On applying breaks, car A stops after 1000 m and car B stops after 1500 m . If FA\mathrm{F}_{\mathrm{A}} and FB\mathrm{F}_{\mathrm{B}} are the forces applied by the breaks on cars A and B , respectively, then the ratio FA/FB\mathrm{F}_{\mathrm{A}} / \mathrm{F}_{\mathrm{B}} is :

Options

  1. A32\frac{3}{2}
  2. B23\frac{2}{3}
  3. C13\frac{1}{3}
  4. D12\frac{1}{2}

Correct answer

B. 23\frac{2}{3}

Step-by-step solution

∵ W.D. =ΔKE\begin{aligned} & \because \text{ W.D. }=\Delta \mathrm{KE} \\ \end{aligned}\overrightarrow{\mathrm{F}} . \overrightarrow{\mathrm{S}}=\Delta \mathrm{KE} (ΔKE)A(ΔKE)B=−FASA−FBSB−100−225=−FA(1000)−FB(1500)FAFB=23\begin{aligned} & \frac{(\Delta K E)_A}{(\Delta K E)_B}=\frac{-\mathrm{F}_A S_A}{-\mathrm{F}_{\mathrm{B}} \mathrm{ S}_{\mathrm{B}}} \\ & \frac{-100}{-225}=\frac{-\mathrm{F}_{\mathrm{A}}(1000)}{-\mathrm{F}_{\mathrm{B}}(1500)} \\ & \frac{\mathrm{F}_{\mathrm{A}}}{\mathrm{ F}_{\mathrm{B}}}=\frac{2}{3} \end{aligned}$
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