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7.Gravitation
medium
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 $2\, m/s$. When the stone reaches the floor, the distance of the man above the floor will be ...... $m$
A
$9.9$
B
$10.1$
C
$10$
D
$20$
(AIPMT-2010)
Solution
Since the man is in gravity free space, $force\,\, on\,\, man + stone\,\, system$ is zero.
Therefore center of mass of the system remains at rest. Let tha man goes $x$ m above when the stone reches the floor, then
${M_{man}} \times x = {M_{stone}} \times 10$
$x = \frac{{0.5}}{{50}} \times 10$
$x\,\,=\,0.1\,\,m$
Therefore final height of man above floor $\,=\,\,10\,+\,\,x\,\,=\,\,10\,+\,0.1\,\,=\,\,10.1\,\,m$
Standard 11
Physics
