Motion in a Straight Line - Result Question 39

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40. 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:

======= ####40. 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:

3e0f7ab6f6a50373c3f2dbda6ca2533482a77bed:content/english/neet-pyq-chapterwise/physics/motion-in-a-straight-line/motion-in-a-straight-line—result-question-39.md (a) $9.9 m$

(b) $10.1 m$

(c) $10 m$

(d) $20 m$

[2010]

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Answer:

Correct Answer: 40. (b)

Solution:

  1. (b) No external force is acting, therefore, momentum is conserved.

By momentum conservation,

$50 u+0.5 \times 2=0$

where $u$ is the velocity of man.

$u=-\frac{1}{50} ms^{-1}$

Negative sign of $u$ shows that man moves upward.

Time taken by the stone to reach the ground

$=\frac{10}{2}=5 sec$

tance moved by the man $=5 \times \frac{1}{50}=0.1 m$

$\therefore \quad$ when the stone reaches the floor, the distance of the man above floor $=10.1 m$