A balloon is rising vertically upward with constant speed 10 m s⁻¹. When it is 120 m above the ground, a stone is released. Taking g = 10 m s⁻², the stone reaches the ground after:
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A balloon is rising vertically upward with constant speed 10 m s⁻¹. When it is 120 m above the ground, a stone is released. Taking g = 10 m s⁻², the stone reaches the ground after:

G1 Physics · Accepted Answer

At release, the stone has upward velocity 10 m s⁻¹. Taking upward as positive and ground 120 m below: −120 = 10t − 5t². Thus t² − 2t − 24 = 0, giving t = 6 s.