Slide 2 of 12
This red rectangles on this graph are the 1-dimensional positions of a cart on an air track, as measured once every two seconds. The curved red line is just a smooth curve passing through the measured points, and represents the continuously changing position of the cart on the track. The cart is released at time t=0 at the left-hand end of the track, which is taken to be the origin. The curved red line is a smooth curve passing through the measured points. The air track is 2 meters long. After leveling the track, its left-hand end was raised a less than 1 centimeter to produce a slight tilt.