A man of 50 kg mass is standing in a gravity free space at a height of 10 m above the floor. He thro

Question

A man of 50 kg mass is standing in a gravity free space at a height of 10 m above the floor. He throws a stone of 0.5 kg mass downwards with a speed $2 \mathrm{~m} / \mathrm{s}$. When the stone reaches the floor, the distance of the man above the floor will be\

Professor PC Thomas Classes · Answer

(b) : Since the man is in gravity free space, force on man + stone system is zero.\ Therefore centre of mass of the system remains at rest. Let the man goes $x \mathrm{~m}$ above when the stone reaches the floor, then $$ \begin{aligned} & M_{\operatorname{man}} 	imes x=M_{	ext {stone }} 	imes 10 \ & x=\frac{0.5}{50} 	imes 10 \quad 	ext { or } \quad x=0.1 \mathrm{~m} \end{aligned} $$ Therefore final height of man above floor $$ \begin{aligned} & =10+x \ & =10+0.1=10.1 \mathrm{~m} \end{aligned} $$