Question

A fireman of mass 60 kg slides down a pole. He is pressing the pole with a force of 600 N. The coefficient of friction between the hands and the pole is 0.5, with what acceleration will the fireman slide down ($g=10m/s^2$)

• A. $1m/s^2$
• B. $2.5m/s^2$
• C. $10m/s^2$
• D. $5m/s^2$

Answer 1

The correct option is D $5m/s^2$

Given: a fireman of mass 60 kg slides down a pole. He is pressing the pole with a force of 600 N. The coefficient of friction between the hands and the pole is 0.5

To find with what acceleration will the fireman slide down

Solution:

Here mass, $m=60kg$

and coefficient of friction, $\mu =0.5=\frac{1}{2}$

and $g=10m/s^2$

Force applied by fireman, $F=600N$

Friction Force, $f=\mu mg=\frac{1}{2}\times 60\times 10=300N$

Net movement force,

$F-f=ma⟹600-300=ma⟹a=\frac{300}{60}⟹a=5m/s^2$

Hence the acceleration with which the fireman slide down is $5m/s^2$