long before newton, galileo galilei determined the first laws of physics – including the acceleration of falling objects (the total distance covered, starting from rest, is proportional to the square of the time) and that a mass moves at a constant speend unless acted upon by another (like friction). he performed his experiments by rolling metal balls down inclined planes and accurately measuring their speed. in this inclined plane from the museum of the history of science in florence, the inclined plane serves as a demo: as the ball rolls down, it strikes bells along the track. although each bell is twice as far from the last, they sound at regular intervals, making gravity audible.