Kinematic question

1. Sep 12, 2007

grewas8

1. The problem statement, all variables and given/known data

The height of a helicopter above the ground is given by h = 2.60t3 , where h is in meters and t is in seconds. After 2.00 s, the helicopter releases a small mailbag. How long after its release does the mailbag reach the ground?

2. Relevant equations

yf=y(initial) + v*delta t

3. The attempt at a solution

h = 2.60 (8) = 20.8 (height at the bag is released)
y(initial)=0
v= 7.8t^2= 31.2 m/s
i dun understand if gravity would be used here and if it is can u just use the quadratic eqn

2. Sep 12, 2007

learningphysics

Everything you did looks good. Yes, you'll have to use the quadratic equation.

3. Sep 12, 2007

learningphysics

this equation isn't right since velocity isn't constant... but you didn't use this equation.