posted by melissa .
a ball rolls horizontally with a speed of 7.6 m/s off the edge of a tall platform. if the ball lands 8.7 m from the point on the ground directly below the edge of the platform, what is the height of the platform?
the horizontal speed never changes, so you can figure out how long it is in the air by distance = rate times time
then figure out how far it fell in that amount of time starting with zero vertical velocity.