Let the seagull be flying along the horizontal when it pooped.
Due to gravity poop starts falling in the downward vertical direction. Let the height of the seagull at that instant of time be
As we are required to find out height
1. From the time it started to fall to the time it hits the ground, acceleration due to gravity
2. We ignore drag due to atmosphere.
Initial Potential energy of the poop
When it hits the ground it potential energy
Change in potential energy between the two positions
We know that Kinetic energy
Initial velocity in the vertical is
Final kinetic energy
Change in Kinetic energy
Due to the law of conservation of energy,
Change in potential energy