Describe Galileo's experiment of an inclined plane regarding motion.

(N/A) To study the motion of an object on an inclined plane,Galileo performed two experiments.
First Experiment:
As shown in the figure,he arranged two planes at the same inclination and allowed a spherical object to move along the incline. His observations were as follows:
$(1)$ $A$ sphere moving down an incline has accelerated motion; hence,its velocity increases.
$(2)$ $A$ sphere moving upward on an incline has retarded motion; hence,its velocity decreases.
$(3)$ For a sphere moving on a horizontal surface,it is an intermediate condition. From this,Galileo concluded that for a body moving on a frictionless horizontal surface,there is no acceleration or retardation. He concluded that the body will continue its motion with a constant velocity.
Second Experiment:
As shown in the figure,two planes with some slope are considered.
When a body is allowed to move from rest on the slope,its velocity increases,and on the opposite slope,its velocity decreases.
If both planes are smooth,the height attained on the second plane will be equal to the height of the first plane from where it was dropped. (It can be less,but it can never be more than the height from where it was dropped.)
In an ideal condition,when there is no friction,the height attained by the ball will be equal to the initial height.