Physics question? HELP.?

Question

A helicopter is ascending vertically with a speed of 6.00 m/s. At a height of 85 m above the Earth, a package is dropped from a window. How much time does it take for the package to reach the ground? [Hint: The package's initial speed equals the helicopter's.]

I got the time from when velocity is 0 in midair, then doubled it to complete the arc, got 1.2 seconds in air. But how to figure out how to go the rest of the way down?

Answer 1

The correct answer is 3 seconds.

Answer 2

Use the equation:

distance = initial_velocity * time + 1/2*acceleration*time^2

d= -85, velocity = 6, acceleration = -9.81 (negative signs because I defined "down" as negative, and "up" as positive)

-85 = 6*t + .5*(-9.81)*t^2

Bring things to the right side of the equation by adding 85 to each side:

0 = -4.905*t^2 + 6*t + 85

This is a quadratic equation in terms of "t".  Solve for it using the quadratic formula or graphing.  You'll get two answers, but one is negative: since time can't be negative, just take the positive value, which is:

t = 4.82 seconds

Hope this helps.