# physics

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A ball is released from a hot air balloon moving downward with a velocity of
-10.0 meters/second and a height of 1,000 meters. How long did it take the ball to reach the surface of Earth? Given: g = -9.8 meters/second2.

• physics -

hf=hi+vi*t+1/2 a t^2
0=1000-10t-4.9t^2

t=(-10+-sqrt(100+19600))/-9.8
t=-150/-9.8=15.3sec

check that.

• physics -

incorrect

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