A balloon is moving vertically upward with constant speed 20 m s⁻¹. When it is 60 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 moving vertically upward with constant speed 20 m s⁻¹. When it is 60 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 20 m s⁻¹. Its height after time t is y = 60 + 20t − 5t². At the ground y=0: t²−4t−12=0. The positive root is t=6 s.