Projectile motion of a flying plane

[ripper9100]

Homework Statement

An airplane is flying with a velocity of 90.0m/s at an angle of 23 degrees w/ the horizontal. When the plane is 114 m directly above a dog that is standing on level ground, a suitcase drops out of the luggage compartment . How far from the dog will the suitcase land? You can ignore air resistance.

The Attempt at a Solution

The initial vertical speed of the plane is 35.2 m/s and the initial horizontal speed of the plane is 82.8 m/s. But I am confused is the initial velocity of the suitcase going to be the same as the plane's or 0.

 

[Dick]

The initial velocity of the suitcase will be the same as that of the plane. Since it was dropped, not thrown.

 

[ripper9100]

thats what i thought but then i get stuck when i try to find the time it takes th suitcase to drop the 114 meters.

114 = 35.2t+.5(-9.8)t^2 is this the right equation?

 

[mbrmbrg]

The signs in your equation may be right, or maybe not.
Which is the positive direction?
Where is y=0?
On third re-reading... I don't see at all how you made your signs agree. You need one of your positives to be a negative.

 

[Dick]

As mbrmbrg points out, looking at the RHS I would say you put your origin at the point where the suitcase was dropped with postive directions up and ahead of the planes motion. In this case the vertical coordinate of the dog should be negative, right?