Physics · Work, Power & Energy

NEET (UG) 2025 — Question 5

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

Option A:
$\frac{3}{2}$
Option B:
$\frac{2}{3}$
Correct
Option C:
$\frac{1}{3}$
Option D:
$\frac{1}{2}$

Answer: B

Step-by-step solution

$\because$ W.D. $=\Delta \mathrm{KE}$

$\overrightarrow{\mathrm{F}} . \overrightarrow{\mathrm{S}}=\Delta \mathrm{KE}$

$\frac{(\Delta K E)_{A}}{(\Delta K E)_{B}}=\frac{-F_{A} S_{A}}{-F_{B} S_{B}}$

$\frac{-100}{-225}=\frac{-\mathrm{F}_{\mathrm{A}}(1000)}{-\mathrm{F}_{\mathrm{B}}(1500)}$

$\frac{\mathrm{F}_{\mathrm{A}}}{\mathrm{F}_{\mathrm{B}}}=\frac{2}{3}$

Answer key and solution verified before publishing.

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Exam: NEET (UG) 2025
Paper: 2025 paper
Subject: Physics
Chapter: Work, Power & Energy
Topic: Kinetic Energy and Work-Energy Theorem