Laws Of Motion Question 430

Question: A balloon with mass M is descending down with an acceleration a (a < g). What mass’ of its contents must be removed so that it starts moving up with same acceleration a

Options:

A)$ \frac{2M( g )}{a} $

B) $ \frac{M( g+a )}{g} $

C)$ \frac{Mg}{g+a} $

D) $ \frac{2Ma}{g+a} $

Show Answer

Answer:

Correct Answer: D

Solution:

[d]

Up thrust F will remain same in both the cases.

Equations of motion be:

$ MgF=Ma $ …(1)

and$ F-(M-m)g=(M-m)a $ …(2)

solving equations (1) and (2) we get, mass to be removed $ m=\frac{2Ma}{g+a} $



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