Question

With what minimum acceleration can a fireman slide down a rope whose breaking strength is two third of his weight?

• A. $\frac{g}{2}$
• B. $\frac{2}{3}g$
• C. $\frac{3}{2}g$
• D. $\frac{g}{3}$

Answer 1

The correct option is D $\frac{g}{3}$

Net downward force in the string, $ma=mg-T$
But $T_{min}=\frac{2}{3}mg$
$\therefore m{a}_{min}=mg-\frac{2}{3}mg$
$a_{min}=g-\frac{2}{3}g=\frac{g}{3}$