Posted by **Jen** on Sunday, October 24, 2010 at 2:47pm.

A helicopter is ascending vertically with a speed of 9.00 m/s. At a height of 90 m above the Earth, a package is dropped from a window. How much time does it take for the package to reach the ground?

- Physics -
**Henry**, Monday, October 25, 2010 at 10:34pm
d = Vo*t + 0.5*9.8t^2 = 90 m,

9*t + 0.5*9.8t^2 = 90,

9t + 4.9t^2 - 90 = 0,

4.9t^2 + 9t - 90 = 0,

Solve for t using quad. Formula & get:

t = 3.46 s.

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