Abstract: An improved appliance for instruction concerning the physical laws relating to the acceleration of a moving object under gravity includes an angle-adjustable slope body, a driving means for raising the slope body to a predetermined angle, a track way provided on the slope body, a moving object slidably riding on the track, and a gear mechanism with angle display where the angle of inclination of the track can be obtained from the angle display accurately to two decimal points. The appliance further includes three sensors corresponding with two timers for measuring the time needed for the moving object to slide a determined distance past the sensors, and a digital display for showing the results so that the acceleration of a moving object can be calculated accurately and easily from the data according to experiments done using the invention.