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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’?
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2ma g + a -
2ma g - a -
ma g + a -
ma g - a
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Correct Option: A
Let upthrust of air be Fa then
For downward motion of balloon
Fa = mg – ma
mg – Fa = ma
For upward motion
Fa – (m – ∆m)g = (m – ∆m)a
| Therefore ∆m = | ||
| g + a |
