Q. With what minimum acceleration can a fireman slide down a rope while breaking $\ $strength of the rope is$\ \frac{2}{3}\ $of the weight?
A) $\frac{2}{3}g$
B) $g$
C) $\frac{1}{3}g$
D) Zero
Explanation
(c) If man slides down with some acceleration, then its apparent weight decreases. For critical condition rope can bear only 2/3 of his weight. If $a$ is the minimum acceleration, then tension in the rope$= m(g - a)$ breaking strength
$\Longrightarrow m(g - a) = \frac{2}{3}mg$
$\Longrightarrow a = g - \frac{2g}{3} = \frac{g}{3}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.