Laws Of Motion Question 276
Question: A balloon with mass ’m’ is descending down with an acceleration ‘a’ (where a < g). How much mass should be removed from it so that it starts moving up with an acceleration ‘a’?
Options:
A) $ \frac{2ma}{g+a} $
B) $ \frac{2ma}{g-a} $
C) $ \frac{ma}{g+a} $
D) $ \frac{ma}{g-a} $
Show Answer
Answer:
Correct Answer: A
Solution:
[a] Let up thrust of air be
$ ~F _{a} $ then For downward motion of balloon $ F _{a}=mg-ma $
$ mg-F _{a}=ma $
For upward motion $ F _{a}-( m-\Delta m )g=( m-\Delta m )a $
Therefore $ \Delta m=\frac{2ma}{g+a} $
