# Homework Help: Object dropped from plane - where does it land?

1. Sep 14, 2008

### x^2

1. The problem statement, all variables and given/known data
A plane is dropping an object from a height of 227m, such that it lands at a group of people on the ground. The speed of the plane is 60 m/s. How many meters before the group does the plane have to drop the object such that it lands at their position?

2. Relevant equations
xf = xi + vix delta t + (1/2) ax(delta t)2

3. The attempt at a solution

From my understanding, I need to break up the x and y components of this problem. If I can find the time it takes the object to hit the ground, I can multiply it by the plane's velocity and see what distance the plane must be from the observers for the package to hit its target.

227 m = 9.8t m/s^2
(227 m)/(9.8 m/s^2) = t
t^2 = 23.162
t = sqrt(23.162)
t = 4.813 seconds

Now that I have the time it took for the object to fall, I can multiply it by the plane's velocity to see how far in the x direction the object will travel in 4.813 seconds:

4.813 s * 60 m/s = 288.78 m

This is the answer I get, but it isn't correct. I can't see how multiplying the velocity by the time is wrong, but perhaps I have the wrong time?

Thanks,
x^2

2. Sep 14, 2008

### Redbelly98

Staff Emeritus
Something is wrong with that equation, since the units are different on the 2 sides:

m ≠ s ⋅ m/s^2
m ≠ m/s