The device that is commonly used to drop a ball down an incline plane from a stationary position is called a ramp or a inclined plane.
The device that is commonly used to drop a ball down an incline plane from a stationary position is called a "release mechanism" or a "ball release mechanism." The release mechanism can be mechanical or manual, and its purpose is to hold the ball in place at the top of the incline plane and then release it to start rolling down the slope when triggered.
